Symptoms

Symptoms of a P2021 engine code may include:

• Malfunction Indicator Lamp (MIL) illuminated
• Lack of power
• Poor fuel economy

Causes

Typically, the causes for this code to set are:

• Faulty IMRC actuator relay (if applicable), bank 2
• Faulty IMRC actuator/sensor bank 2
• Rarely – Faulty Powertrain Control Module (PCM)
• (Programming required after replacement)

Diagnostic Steps

and Repair Information

A good starting point is always to check the Technical Service Bulletins (TSBs) for your specific vehicle. Your issue might be a known problem with a known fix released by the manufacturer and could save you time and money during diagnosis.

The next step in this process is to locate the Bank 2 IMRC valve/sensor on your specific vehicle. Once located, visually inspect the connectors and wiring. Look for chafing, scraping, bare wires, worn spots, or melted plastic connectors. Separate the connectors and carefully inspect the terminals (the metal parts) inside the connectors. Verify they are not burnt or corroded. If in doubt, obtain an electrical contact cleaner from any auto parts store if terminal cleaning is necessary. If not possible, get some rubbing alcohol and a small plastic-bristled brush (used toothbrush) to clean them. Once cleaned, let them air dry. Pack the connector cavity with a dielectric silicone compound (same as used for light bulb sockets and spark plug wires) and reassemble.

If you have a scan tool, clear the diagnostic codes from the memory and see if this code returns. If it does not, the connections were likely your problem.

If the code returns, we will need to test the voltage signals to and from the IMRC valve to the PCM. Monitor the IMRC valve voltage on your scan tool. If a scan tool is not available, test the signal going to the IMRC valve with a Digital Volt Ohm Meter (DVOM). With the valve disconnected, the red voltmeter lead should be attached to the IMRC valve power supply wire and the black voltmeter lead connected to ground. Turn the ignition switch to the “on” position and check the voltage. It should be fairly close to battery voltage (12 volts). If not, the circuit has the problem. If it has 12 volts, reconnect the wires to the valve and check the voltage on the ground wire (PCM control wire). It should also be fairly close to battery volts. If not, the IMRC valve/solenoid is suspected to be open/shorted at this point.

If all tests have passed so far and you still have the same code, check your scan tool and see if it can open and close the IMRC valve. This might be called an “actuator test,” “bi-directional test,” or “functional test” depending on the scan tool/vehicle manufacturer. If the scan tool has this capability and it can operate the IMRC valves, the problem is either resolved and a simple code clearing is all that remains, or a new PCM would be required. If the scan tool has the capability but is unable to move the valves, either a faulty ground circuit between the valve and the PCM is indicated, or a faulty PCM.

It cannot be overemphasized that once the first or first couple of diagnostic steps are performed and the problem is not obvious, it would be wise to consult an automotive professional regarding the repair of your vehicle, as repairs from this point may require the removal of the intake manifold in order to properly diagnose this code and the related engine performance issue.

Symptoms

Symptoms of a P2023 engine code may include:

• Malfunction Indicator Lamp (MIL) illuminated
• Lack of power
• Occasional misfires
• Poor fuel economy

Causes

Typically, the causes for this code to set are as follows:

• Sticking/faulty throttle plates/body
• Sticking/faulty IMRC valve assembly 2
• Faulty IMRC actuator/sensor bank 2
• Rarely – Faulty Powertrain Control Module (PCM)
• (Programming required after replacement)

Diagnostic Steps

and Repair Information

A good starting point is always to check the Technical Service Bulletins (TSBs) for your specific vehicle. Your issue may be a known problem with a known fix released by the manufacturer and can save you time and money during diagnosis.

The most common failure items (and the most often misdiagnosed items) on these systems are: the IMRC vacuum solenoids, as carbon builds up inside the vent portion and does not allow them to vent properly at all, and the second is that the IMRC plates stick/bind due to carbon deposits around them.

First, note if there are any other diagnostic trouble codes. If any of them are related to the intake/engine performance system, diagnose them first. Misdiagnosis is known to occur if a technician diagnoses this code before any intake/engine performance-related system codes have been thoroughly diagnosed and dismissed. Ensure there is no intake or exhaust leak. An intake leak, or vacuum leak, causes the engine to idle roughly. An exhaust leak gives the impression of a lean-running engine by the air/fuel ratio (AFR/O2) sensor.

The next step in this process is to locate the IMRC valve/sensor for bank 2 on your specific vehicle. Once located, visually inspect the connectors and wiring. Look for chafing, scuffs, bare wires, worn spots, or melted plastic connectors. Separate the connectors and carefully inspect the terminals (the metal parts) inside the connectors. Check that they are not burnt or corroded. If in doubt, obtain an electrical contact cleaner from any auto parts store if terminal cleaning is necessary. If not possible, get rubbing alcohol and a small plastic-bristled brush (used toothbrush) to clean them. Once cleaned, let them air dry. Pack the connector cavity with dielectric silicone compound (same as used for bulb sockets and spark plug wires) and reassemble.

If you have a scan tool, clear the diagnostic codes from memory and see if this code returns. If not, the connections were likely your problem.

If the code returns, we will need to test the voltage signals of the IMRC valve/sensor to and from the PCM. Monitor the IMRC sensor voltage on your scan tool. If no scan tool is available, test the signal from the IMRC sensor with a digital voltmeter (DVOM). With the sensor connected, the red voltmeter lead should be attached to the IMRC sensor signal wire and the black voltmeter lead connected to ground. Start the engine and monitor the IMRC sensor input. Snap the throttle. As engine RPM increases, the IMRC sensor signal should change. Check manufacturer specifications, as there may be a chart informing you of the voltage at a given RPM.

If it fails this test, you will need to verify that the IMRC valve will move and is not stuck or binding inside the intake manifold. Remove the IMRC sensor/actuator and grasp the pin or linkage that moves the plates/valves inside the intake manifold. Keep in mind that these may have a strong return spring, so there may be tension when you turn them. Check if the plates/valves are stuck/loose when you turn them. If so, you will need to replace them, and this usually means you will have to replace the entire intake manifold. It is best to leave this task to professionals.

If the IMRC plates/valves turn without any binding or excessive looseness, this would indicate the need to replace the IMRC sensor/actuator and retest.

Again, it cannot be stressed enough that all other codes should be diagnosed before this one, as issues causing other codes to set can also cause this one. It cannot be overemphasized that once the first or first couple of diagnostic steps are performed and the problem is not obvious, it would be wise to consult an automotive professional regarding the repair of your vehicle, as most repairs from this point forward will require the removal and replacement of the intake manifold in order to properly fix this code and the related engine performance issue.

How severe is this DTC?

As with most EVAP faults, I would say it’s low on the severity scale. The entire system was primarily designed to reduce emissions into the atmosphere. Obviously, it does much more in the meantime, but all that said, really the only thing negatively affected by this fault is the atmosphere. At the moment, I can’t think of any EVAP system issue that could harm the overall safety of the vehicle. This does NOT mean you can keep driving the vehicle day after day without addressing the problem. One problem always leads to another if left unresolved for too long.

What are some of the symptoms of the code?

Symptoms of a P2024 trouble code may include:

• State/provincial emissions test failure
• Check Engine Light (CEL) on
• Slight decrease in fuel efficiency
• Fuel odor
• Possible abnormal fuel filling symptoms (long fill times, unable to fully squeeze the gas pump trigger, etc.)

What are some common causes of the code?

Causes of this P2024 fuel compensation code may include:

• Faulty EVAP fuel vapor temperature sensor
• Obstruction/leak in the system causing sensor operation out of range (mainly P2025)
• Broken or damaged EVAP fuel vapor temperature sensor wiring harness
• Short circuit in the power wire
• Excessive resistance in the circuit
• ECM (Engine Control Module) problem
• Pin/connector issue (corrosion, melting, broken locking tab, etc.)

How to troubleshoot and repair a P2024 code?

As mentioned above, the overall health of the EVAP system is of great importance. Check that the involved components are not obstructed and that there are no visible cracks in the plastic pipes. It would be a good idea to locate where the EVAP system gets its fresh atmospheric air to introduce into the system to regulate pressure differences. In some cases, most parts used in this system will be located under the vehicle. I would recommend using wheel ramps rather than a hydraulic jack due to their convenience and especially the safety benefits.

NOTE: Be careful when disconnecting/handling EVAP hoses and pipes. Often, they may seem fine until you try to disconnect them and a clip or the entire hose breaks, and now you have to replace/repair something to proceed with your diagnostics. Be extremely careful here.

Test the sensor. From my experience, the ECM uses the voltage readings from the EVAP fuel vapor temperature sensor to monitor temperatures. That said, there is most likely a specific pin test that can be performed to check the sensor’s functionality.

How severe is this DTC?

As with most EVAP faults, I’d say it’s low on the severity scale. The entire system was primarily designed to reduce emissions into the atmosphere. Obviously, it does much more in the meantime, but all that said, really the only thing negatively affected by this fault is the atmosphere. At the moment, I can’t think of any EVAP system issue that could harm the overall safety of the vehicle. This does NOT mean you can keep driving the vehicle day after day without addressing the problem. One problem always leads to another if left unresolved for too long.

What are some of the symptoms of the code?

Symptoms of a P2025 trouble code may include:

• State/provincial emissions test failure
• Check Engine Light (CEL) illuminated
• Slight decrease in fuel efficiency
• Fuel odor
• Possible abnormal fuel filling symptoms (long fill times, unable to fully pull the gas pump trigger, etc.)

What are some common causes of the code?

Causes of this P2025 fuel compensation code may include:

• Faulty EVAP (Evaporative Emissions) fuel vapor temperature sensor
• Obstruction/leak in the system causing sensor operation out of range (mainly for P2025)
• Broken or damaged EVAP fuel vapor temperature sensor wiring harness
• Short circuit in the power wire
• Excessive resistance in the circuit
• ECM (Engine Control Module) problem
• Pin/connector issue (corrosion, melting, broken locking tab, etc.)

How to troubleshoot and repair a P2025 code?

As mentioned above, the overall health of the EVAP (Evaporative Emissions) system is of great importance. Check that the involved components are not obstructed and that there are no visible cracks in the plastic pipes. It would be a good idea to locate where the EVAP system gets its fresh atmospheric air to introduce into the system to regulate pressure differences. In some cases, most parts used in this system will be located under the vehicle. I would recommend using wheel ramps rather than a hydraulic jack due to their convenience and especially the safety benefits.

NOTE: Be careful when disconnecting/handling EVAP hoses and pipes. Often, they may appear healthy until you try to disconnect them and a clip or the entire hose breaks, and you now have to replace/repair something to proceed further with your diagnostics. Be extremely careful here.

Test the sensor. From my experience, the ECM uses the EVAP fuel vapor temperature sensor’s voltage readings to monitor temperatures. That said, there is most likely a specific pin test that can be performed to check the sensor’s functionality.

Understanding the Lexus P1443 Diagnostic Trouble Code

The P1443 diagnostic trouble code is a manufacturer-specific code that primarily affects Lexus and Toyota vehicles. This code indicates a malfunction within the Evaporative Emission Control System (EVAP), specifically related to the vapor pressure sensor circuit or the Vent Control Valve (VCV) system. When this code appears, it signifies that your vehicle’s Engine Control Module (ECM) has detected an irregularity in the monitoring of fuel vapor pressure or the operation of the vent control system.

What Does P1443 Mean for Your Lexus?

P1443 specifically points to a problem in the EVAP system’s ability to properly monitor and control fuel vapors. The EVAP system is designed to prevent gasoline vapors from escaping into the atmosphere by storing them in a charcoal canister and later purging them into the engine for combustion. When the P1443 code triggers, it means the ECM has detected an electrical or mechanical fault in either the vapor pressure sensor circuit or the vent control valve operation, compromising the system’s efficiency and environmental compliance.

Technical Background of EVAP System Operation

The EVAP system in modern Lexus vehicles is a sophisticated network of components working together to control fuel vapor emissions. The system includes the fuel tank, charcoal canister, purge valve, vent valve, and various sensors including the vapor pressure sensor. The ECM continuously monitors these components during specific drive cycles, and when it detects voltage readings or operational patterns outside predetermined parameters, it stores the P1443 code and illuminates the check engine light.

Common Symptoms and Immediate Effects of P1443

When the P1443 code appears in your Lexus, you may notice several symptoms that indicate the EVAP system isn’t functioning optimally. While some symptoms might be subtle initially, they can progressively worsen if left unaddressed, potentially leading to more significant issues with your vehicle’s performance and emission compliance.

Primary Symptoms of P1443 Code

• Illuminated check engine light on your dashboard
• Possible fuel odor around the vehicle
• Reduced fuel efficiency over time
• Failed emissions testing in regions requiring compliance checks
• Rough idling or occasional engine performance issues
• Difficulty refueling due to vapor lock in severe cases

Secondary Effects on Vehicle Performance

While the P1443 code primarily affects emission control rather than direct engine performance, prolonged neglect can lead to secondary issues. The ECM may enter a fail-safe mode that could slightly impact fuel trims and engine calibration. Additionally, since the EVAP system is interconnected with the fuel delivery system, you might experience minor drivability concerns, particularly during specific driving conditions where the system would normally purge fuel vapors.

Comprehensive Diagnosis and Troubleshooting Procedures

Proper diagnosis of the P1443 code requires a systematic approach using appropriate diagnostic tools and following manufacturer-recommended procedures. This process involves electrical testing, component inspection, and functional verification to accurately identify the root cause before proceeding with repairs.

Initial Diagnostic Steps and Safety Precautions

• Begin with a professional OBD2 scanner to confirm the P1443 code and check for any additional codes
• Perform a thorough visual inspection of EVAP system components and wiring harnesses
• Check for technical service bulletins specific to your Lexus model and year
• Ensure the gas cap is properly sealed before proceeding with advanced diagnostics
• Verify battery voltage and ground connections to eliminate electrical supply issues

Advanced Electrical Testing Procedures

Using a digital multimeter, technicians should test the vapor pressure sensor and vent control valve circuits according to Lexus service manual specifications. This includes checking reference voltage (typically 5V), signal return circuits, and ground connections. Resistance testing of the vapor pressure sensor and vent control valve should be performed, with values compared against factory specifications. Continuity testing of wiring harnesses between the ECM and affected components is crucial to identify potential opens or shorts.

Functional Testing and Component Verification

Beyond electrical testing, functional verification using a smoke machine can identify vacuum leaks in the EVAP system. Applying vacuum directly to the vent control valve while monitoring its operation can confirm mechanical functionality. Using bidirectional scanner controls to activate the vent control valve allows verification of its operational response. Pressure testing the EVAP system can reveal leaks or restrictions that might contribute to the P1443 code.

Common Causes and Repair Solutions for P1443

The P1443 code can result from various issues within the EVAP system, ranging from simple electrical connections to component failures. Understanding these potential causes helps technicians develop an efficient repair strategy and prevents unnecessary part replacement.

Most Frequent Causes of P1443 in Lexus Vehicles

• Failed vapor pressure sensor providing incorrect readings to the ECM
• Malfunctioning vent control valve (VSV) stuck open or closed
• Damaged wiring harness or connectors in the EVAP system circuit
• Blocked or restricted EVAP vent lines or hoses
• Faulty charcoal canister affecting system pressure
• Corroded electrical connections at sensor or valve terminals
• ECM software issues requiring updates or recalibration

Step-by-Step Repair Procedures

Begin repairs by addressing the most accessible and common causes first. Replace the vapor pressure sensor if testing confirms it’s out of specification. Install a new vent control valve if it fails electrical or functional testing. Repair any damaged wiring harnesses using proper splicing techniques and weatherproof connectors. Clear the diagnostic trouble codes after repairs and perform a complete drive cycle to verify the fix. Always use OEM or high-quality aftermarket parts to ensure longevity and proper system operation.

Preventive Maintenance and Long-Term Solutions

Preventing recurrence of the P1443 code involves regular maintenance and awareness of factors that can compromise your Lexus EVAP system. While some components have a finite lifespan, proper care can extend their service life and maintain optimal emission system performance.

EVAP System Maintenance Best Practices

• Always ensure the gas cap is properly tightened after refueling
• Address any fuel system issues promptly to prevent additional strain on EVAP components
• Include EVAP system inspection during routine maintenance schedules
• Avoid overfilling the fuel tank beyond the automatic shutoff
• Keep the engine compartment clean to prevent debris accumulation around EVAP components
• Use quality fuel from reputable stations to maintain system cleanliness

When to Seek Professional Assistance

While some automotive enthusiasts may attempt basic diagnosis, the complexity of modern EVAP systems often requires professional expertise. If you lack specialized diagnostic equipment or encounter difficulties during testing, consulting a certified Lexus technician is advisable. Dealership technicians have access to technical service bulletins, specialized tools, and factory training that can streamline diagnosis and ensure proper repair execution, ultimately saving time and preventing misdiagnosis.

Successfully addressing the P1443 code in your Lexus requires methodical diagnosis, quality parts, and proper repair techniques. By understanding the technical aspects of the EVAP system and following structured diagnostic procedures, you can restore your vehicle’s emission control system to optimal operation while maintaining environmental compliance and vehicle performance.

How severe is this DTC?

Like most EVAP faults, I would say it’s low on the severity scale. The entire system was primarily designed to reduce emissions into the atmosphere. Obviously, it does much more in the meantime, but all that said, really the only thing negatively affected by this fault is the atmosphere. At the moment, I can’t think of any EVAP system issue that could harm the overall safety of the vehicle. This does NOT mean you can keep driving the vehicle day after day without addressing the problem. One problem always leads to another if left unresolved for too long.

What are some symptoms of the code?

Symptoms of a P2026 trouble code may include:

• State/provincial emissions test failure
• Check Engine Light (CEL) illuminated
• Slight decrease in fuel efficiency
• Fuel odor
• Possible abnormal fuel filling symptoms (slow fills, unable to fully squeeze the gas pump trigger, etc.)

What are some common causes of the code?

Causes of this P2026 fuel compensation code may include:

• Faulty EVAP (Evaporative Emissions) fuel vapor temperature sensor
• Obstruction/leak in the system causing sensor operation out of range (mainly P2025)
• Broken or damaged EVAP fuel vapor temperature sensor wiring harness
• Short circuit in the power wire
• Excessive resistance in the circuit
• ECM (Engine Control Module) problem
• Pin/connector issue (corrosion, melting, broken locking tab, etc.)

How to troubleshoot and repair a P2026 code?

As mentioned above, the overall health of the EVAP (Evaporative Emissions) system is of great importance. Check that the involved components are not obstructed and that there are no visible cracks in the plastic pipes. It would be a good idea to locate where the EVAP system gets its fresh atmospheric air to introduce into the system to regulate pressure differences. In some cases, most parts used in this system will be located under the vehicle. I would recommend using wheel ramps rather than a hydraulic jack due to their convenience and especially the safety benefits.

NOTE: Be careful when disconnecting/handling EVAP hoses and pipes. Often, they may appear healthy until you try to disconnect them and a clip or the entire hose breaks, and you now have to replace/repair something to proceed further with your diagnostics. Be extremely careful here.

Test the sensor. From my experience, the ECM uses the EVAP fuel vapor temperature sensor’s voltage readings to monitor temperatures. That said, there is most likely a specific pin test that can be performed to check the sensor’s functionality.

How severe is this DTC?

As with most EVAP faults, I would say it’s low on the severity scale. The entire system was primarily designed to reduce emissions into the atmosphere. Obviously, it does much more in the meantime, but all that said, really the only thing negatively affected by this fault is the atmosphere. At the moment, I can’t think of any EVAP system issue that could harm the overall safety of the vehicle. This does NOT mean you can keep driving the vehicle day after day without addressing the problem. One problem always leads to another if it’s not resolved for too long.

What are some of the symptoms of the code?

Symptoms of a P2027 trouble code may include:

• State/provincial emissions test failure
• Check Engine Light (CEL) on
• Slight decrease in fuel efficiency
• Fuel odor
• Possible abnormal fuel filling symptoms (long fill-ups, unable to fully pull the gas pump trigger, etc.)

What are some common causes of the code?

Causes of this P2027 fuel compensation code may include:

• Faulty EVAP (Evaporative Emissions) fuel vapor temperature sensor
• Broken or damaged EVAP fuel vapor temperature sensor wiring harness
• Short circuit in the power wire
• Excessive resistance in the circuit
• ECM (Engine Control Module) problem
• Pin/connector issue (corrosion, melting, broken locking tab, etc.)

How to troubleshoot and repair a P2027 code?

As mentioned above, the overall health of the EVAP (Evaporative Emissions) system is of great importance. Check that the involved components are not clogged and that there are no visible cracks in the plastic pipes. It would be a good idea to locate where the EVAP system gets its fresh atmospheric air to introduce into the system to regulate pressure differences. In some cases, most parts used in this system will be located under the vehicle. I would recommend using wheel ramps rather than a hydraulic jack due to their convenience and especially the safety benefits.

NOTE: Be careful when disconnecting/handling EVAP hoses and pipes. Often, they may seem fine until you try to disconnect them and a clip or the entire hose breaks, and now you have to replace/repair something to proceed further with your diagnostics. Be extremely careful here.

Test the sensor. From my experience, the ECM uses the EVAP fuel vapor temperature sensor’s voltage readings to monitor temperatures. That said, there is most likely a specific pin test that can be performed to check the sensor’s functionality.

How serious is this DTC?

As with most EVAP faults, I would say it’s low on the severity scale. The entire system was primarily designed to reduce emissions into the atmosphere. Obviously, it does much more in the meantime, but all that said, really the only thing negatively affected by this fault is the atmosphere. For now, I can’t think of any EVAP system issue that could harm the overall safety of the vehicle. This does NOT mean you can keep driving the vehicle day after day without addressing the problem. One problem always leads to another if not resolved for too long.

What are some of the symptoms of the code?

Symptoms of a P2028 trouble code may include:

• State/provincial emissions test failure
• Check Engine Light (CEL) on
• Slight decrease in fuel efficiency
• Fuel odor
• Possible abnormal fuel filling symptoms (long fill times, unable to fully pull the gas pump trigger, etc.)

What are some common causes of the code?

Causes of this P2028 fuel compensation code may include:

• Faulty EVAP fuel vapor temperature sensor
• Broken or damaged EVAP fuel vapor temperature sensor wiring harness
• Inconsistent electrical connection, e.g., fuse not properly installed in designated slot, loose connector pin, broken tab on connector, etc.
• Short circuit in the power wire
• Excessive resistance in the circuit
• ECM (Engine Control Module) issue
• Pin/connector problem (corrosion, melting, broken locking tab, etc.)

How to troubleshoot and repair a P2028 code?

As mentioned above, the overall health of the EVAP (Evaporative Emissions) system is of great importance. Check that the involved components are not clogged and that there are no visible cracks in the plastic pipes. It would be a good idea to locate where the EVAP system gets its fresh atmospheric air to introduce into the system to regulate pressure differences. In some cases, most parts used in this system will be located under the vehicle. I would recommend using wheel ramps rather than a hydraulic jack for their convenience and, most importantly, safety benefits.

NOTE: Be careful when disconnecting/handling EVAP hoses and pipes. Often, they may seem fine until you try to disconnect them and a clip or the entire hose breaks, and now you have to replace/repair something to proceed with your diagnostics. Be extremely careful here.

Test the sensor. From my experience, the ECM uses the voltage readings from the EVAP fuel vapor temperature sensor to monitor temperatures. That said, there is most likely a specific pin test that can be performed to check the sensor’s functionality.

How serious is this DTC?

A stored P2029 code will likely be accompanied by a lack of heat in the cabin. The stored code indicates that an electrical issue or a serious mechanical failure has occurred. In very cold weather, the conditions that led to the storage of such a code must be corrected as quickly as possible.

What are some of the symptoms of the code?

Symptoms of a P2029 fault code may include:

• No heat in the cabin
• Excessive heat in the cabin
• The air conditioning fan may be temporarily disabled
• No symptoms may appear
• What are some common causes of the code?

Causes

of this code may include:

• Faulty temperature sensor (air or coolant)
• Faulty fuel heater injector
• Faulty fuel heater burner/igniter
• Shorted or open wiring or connectors in the fuel heater circuit
• Faulty PCM or programming error

What are the troubleshooting steps for P2029?

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be needed to diagnose a P2029 code.

You can use your vehicle information source to locate a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as the engine size, stored codes, and symptoms presented. If you find one, it may provide useful diagnostic information.

Use the scanner (connected to the vehicle’s diagnostic connector) to retrieve all stored codes and relevant freeze frame data. It’s a good idea to record this information before clearing the codes, then test the vehicle until the PCM enters readiness mode or the code resets.

If the PCM enters readiness mode at this point, the code is intermittent and may be much harder to diagnose. If this is the case, the conditions that led to the code being stored may need to worsen before an accurate diagnosis can be made.

If the code is immediately reset, the next step in your diagnosis will require you to search your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, and component testing procedures/specifications.

If the fuel heater has been disabled, the code may need to be cleared immediately before testing.

Step 1
Use the DVOM to test the temperature sensors (air or coolant) according to the manufacturer’s specifications. Sensors that do not test within the allowed parameters should be considered faulty.

Step 2
Use your vehicle diagnostic information source and the DVOM to test the fuel heater injectors and igniters with the system activated. If weather conditions do not allow activation, use the scanner to activate it manually.

Step 3
If the system switches and other components are functional, use the DVOM to test the input and output signal circuits of the fuse panel, PCM, and ignition switch. Disconnect all controllers before using the DVOM for testing.

Fuel heater systems are mainly used in diesel engine vehicles and in extremely cold markets

How severe is this DTC?

A stored P202A code should be considered severe and addressed as soon as possible. The SCR system may be disabled because of this. Catalyst damage could occur if the conditions that contributed to the code being stored are not corrected in a timely manner.

What are some of the symptoms of the code?

Symptoms of a P202A fault code may include:

• Reduced fuel efficiency
• Excessive black smoke from vehicle exhaust
• Decreased engine performance
• Other SCR-related codes

What are some common causes of the code?

Causes of this code may include:

• Faulty reductant tank heater element
• Open or shorted circuits in reductant tank heater control
• Faulty SCR controller/PCM or programming error

What are the troubleshooting steps for P202A?

A diagnostic scanner, digital volt/ohmmeter (DVOM), and vehicle-specific diagnostic information source will be needed to diagnose a P202A code.

You can use your vehicle information source to locate a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as engine size, stored codes, and presented symptoms. If you find one, it may provide helpful diagnostic information.

Use the scanner (connected to the vehicle’s diagnostic connector) to retrieve all stored codes and relevant freeze frame data. It’s a good idea to record this information before clearing the codes, then test drive the vehicle until the PCM enters readiness mode or the code resets.

If the PCM enters readiness mode at that point, the code is intermittent and may be much more difficult to diagnose. If this is the case, the conditions that contributed to the code being stored may need to worsen before an accurate diagnosis can be made.

If the code immediately resets, the next step in your diagnosis will require you to search your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, and component testing procedures/specifications.

Step 1
Use the DVOM to test the reductant tank heater element according to manufacturer specifications. Heaters are typically either blanket-type or pin-type. Heating elements that do not test within allowable maximum parameters should be considered faulty.

Step 2
Use your vehicle diagnostic information source and the DVOM to test the reductant heater circuit voltage (typically battery voltage) with the system activated. If current conditions don’t allow activation, use the scanner to manually activate the heater.

Step 3
If the reductant tank heater is functional, use the DVOM to test the input and output signal circuits of the fuse panel, PCM, and ignition switch. Disconnect all controllers before using the DVOM for testing.

Reductant tank heater systems are used exclusively in diesel-powered vehicles and in colder climates