What does error code P0443 mean?

The diagnostic code P0443 is a generic powertrain code, meaning it applies to all vehicles equipped with an OBD-II system. It indicates a problem in the control circuit of the Evaporative Emission (EVAP) system purge valve.

Operation of the EVAP System and the Purge Valve

The EVAP system is designed to prevent gasoline vapors from the fuel tank from escaping into the atmosphere. Instead, these vapors are directed to the engine to be burned. The purge valve is a key component of this system. It is powered by a switched battery voltage (present when the ignition is on).

The Engine Control Module (ECM) controls the opening and closing of this valve by actuating the ground circuit. At specific times, the ECM grounds the circuit, which allows the valve to open and fuel vapors to be drawn into the engine.

The ECM also monitors the integrity of this ground circuit to detect potential faults. When the purge valve is not activated (at rest), the ECM expects to see a high voltage on the ground circuit. When the valve is activated (grounded by the ECM), the voltage on the ground circuit should drop to a value close to zero. If the ECM does not detect these expected voltages or if it identifies an open circuit (interruption), the code P0443 is stored.

Important Note: This error code is similar to codes P0444 (EVAP purge valve control circuit open) and P0445 (EVAP purge valve control circuit shorted).

Potential Symptoms of Code P0443

The symptoms associated with fault code P0443 can vary:

• The most common symptom is the illumination of the Malfunction Indicator Lamp (MIL or Check Engine Light).
• There may be no noticeable driving issues.
• However, in some cases (if the purge valve is stuck open), you might observe a lean air-fuel mixture or engine misfire. These symptoms are usually accompanied by other EVAP system-related error codes.
• Another possible symptom is excessive pressure in the fuel tank, manifesting as an audible “hiss” or “squeal” when removing the fuel cap. This can indicate a purge valve that is not functioning at all or is stuck in the closed position.

Possible Causes of Code P0443

For a P0443 code to be stored, there must be a problem with the purge CONTROL CIRCUIT, not necessarily with the valve itself. Often, the valve and the control solenoid are integrated into a single unit. In other configurations, it may be a separate solenoid controlling the vacuum routed to a purge valve. That said, possible causes include:

• Faulty purge solenoid (with an internal short circuit or open circuit).
• Damaged wiring harness (rubbing against another component, causing a short or open in the control circuit).
• Worn, broken, or shorted electrical connector (often due to water intrusion or corrosion).
• Failure of the driver circuit inside the Powertrain Control Module (PCM).

Possible Solutions and Diagnostic Steps

Here are possible diagnostic steps to identify and resolve the problem related to code P0443:

1. Activation Test via Scan Tool: Use an OBD-II scan tool to command the activation of the purge solenoid. Listen carefully or try to feel a “click” from the solenoid. It should click once per command, or on some models, it may click repeatedly.
2. Diagnosis if the solenoid does not activate:
   • If no click is heard during activation via the scan tool, unplug the solenoid connector.
   • Visually inspect the solenoid and connector for physical damage, signs of water, or corrosion.
   • Check for battery voltage on the solenoid’s power wire with the ignition on (key in ON position). If voltage is present, proceed to the next step.
   • Manually ground the control side (usually the ground wire) of the solenoid using a test wire (jumper) and see if the valve clicks.
     • If it clicks: This indicates that the solenoid is functioning correctly, but there is a problem in the control circuit (between the ECM and the solenoid).
     • If it does not click: The purge solenoid is likely faulty and needs to be replaced.
3. Checking the Control Circuit (if the solenoid works and power is good):
   • Reconnect the solenoid.
   • Locate and remove the control circuit wire (ground) from the ECM connector. (Caution: If you are unsure of the procedure, do not attempt this step to avoid damaging the ECM).
   • With the solenoid’s ground wire disconnected from the ECM, turn the ignition on (key in ON position).
   • Manually ground the purge valve control wire.
     • If the solenoid clicks: This means there is no problem with the control wire between the ECM and the solenoid. The issue is likely with the purge solenoid control circuit inside the ECM, which will require replacing the ECM.
     • If the solenoid does not click: There is likely an open circuit (break) in the wiring between the ECM and the solenoid. You will need to locate this break and repair it.

Other mentioned EVAP error codes: P0440, P0441, P0442, P0444, P0445, P0446, P0447, P0448, P0449, P0452, P0453, P0455, P0456. These codes indicate other types of problems within the evaporative emission system.

What does it mean?

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On vehicles equipped with Evaporative Emission Control Systems, also known as EVAP, the engine draws excessive fuel vapors from the gas tank that would otherwise be released into the atmosphere.

The fuel vapor is routed via a vacuum line to the engine intake, and the purge valve/solenoid measures the desired amount of fuel vapor, controlled by the Powertrain Control Module (PCM) or Engine Control Module (ECM). The PCM/ECM monitors the voltage to the purge control valve and detected no voltage change with the purge valve activated.

Note: This code is similar to P0443 and P0445 codes.

Symptoms

Symptoms of a P0444 trouble code may include:

Check Engine Light illuminated (Malfunction Indicator Light on)
Slightly reduced fuel economy; this will not affect engine performance

Potential Causes

Causes

of this DTC may include:

Loose or disconnected wiring harness
Open circuit in the engine wiring harness
Open circuit in the purge control solenoid
PCM/ECM malfunction

Diagnostic Steps

for P0444 DTC

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Engine Wiring Harness – Check all connectors to ensure they are properly plugged in, look for loose or damaged wires. Typically, the purge control valve is powered by the battery and triggered on and off with a duty cycle via the PCM/ECM. Using the manufacturer’s wiring diagrams, identify the type of circuit used and check for battery voltage with the key on/engine off on the power side of the purge control solenoid connector using a Digital Volt-Ohm Meter (DVOM) set to the volts scale. If no battery voltage is present, trace the wiring and determine the cause of the voltage loss.

Test the continuity on the control side of the wiring harness after unplugging the solenoid plug from the purge control valve and PCM wiring harness. Identify the correct wire at the PCM and the control valve harness and check continuity using the ohms scale on the DVOM. If excessive resistance is found, repair the circuit. If there is no continuity in the circuit, check all connections for damaged wiring, loose pins, or disconnected harnesses and repair the circuit.

Purge Control Solenoid – Check continuity at the purge control solenoid connector pins after removing the harness plug using the DVOM set to the ohms scale. Verify that the resistance meets the manufacturer’s specifications. If no continuity is present, suspect that the solenoid is open internally and replace the part with a known good unit.

PCM/ECM Malfunction – Since the EVAP is only activated under certain driving conditions, it will be necessary to monitor the EVAP control operation using a capable advanced scan tool and perform a road test under the required driving conditions to activate the EVAP system. Some advanced scan tools have an internal test to manually activate the EVAP system. Verify that the PCM/ECM is commanding the EVAP system. If the system is operating correctly, it will be necessary to probe the PCM/ECM wiring harness connector using a graphing multimeter or oscilloscope with a duty cycle function, with the positive lead on the purge control valve pin and the negative lead connected to a known good ground. The duty cycle should match what is commanded by the PCM/ECM during EVAP operation. If no duty cycle is present, the PCM/ECM may be faulty.

Other EVAP DTCs: P0440 – P0441 – P0442 – P0443 – P0445 – P0446 – P0447 – P0448 – P0449 – P0452 – P0453 – P0455 – P0456

What does it mean?

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On vehicles equipped with Evaporative Emission Control Systems, also known as EVAP, the engine draws excess fuel vapors from the gas tank that would otherwise be released into the atmosphere.

The fuel vapor is routed via a vacuum line to the engine intake, and the purge valve/solenoid measures the desired amount of fuel vapor, controlled by the Powertrain Control Module (PCM) or Engine Control Module (ECM). The PCM/ECM monitors the voltage to the purge control valve and has detected a voltage lower than expected.

Note: This code is similar to P0443 and P0444 codes.

Symptoms

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Symptoms of a P0445 trouble code may include:

Check Engine Light illuminated (Malfunction Indicator Light on)
Slightly reduced fuel economy; this will not affect engine performance

Potential Causes

Causes

of this DTC may include:

Engine wiring harness or connector short circuit
Purge control solenoid short circuit
PCM/ECM malfunction

Diagnostic Steps

for P0445 DTC

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Engine Wiring Harness – Inspect wiring harness connectors for damage, look for pinched wires, loose or bent pins, or bare wiring without insulation. Typically, the purge control valve is powered by the battery and triggered on and off with a duty cycle via the PCM/ECM. Using manufacturer wiring diagrams, identify the type of circuit used and check for battery voltage with the key on/engine off on the power supply side of the purge control solenoid connector using a Digital Volt-Ohm Meter (DVOM) set to the volts scale. If no battery voltage is present, trace the wiring to determine the cause.

Check for a short to ground by disconnecting the harness at the purge control valve solenoid and the voltage source. Using the DVOM set to the ohms scale, with the negative lead connected to a known good ground and the positive lead to each end that powers the purge control valve solenoid. If resistance is very low, suspect a short to ground and repair the wiring harness. Check for a short to ground on the control side of the harness by disconnecting the harness from the purge control valve solenoid and the PCM/ECM harness. Identify the correct wire and using the DVOM set to an ohms scale, check resistance with the negative lead connected to a known good ground and the positive lead on one of the wiring harnesses of the control circuit. If resistance is very low, suspect a short to ground and repair the wiring harness.

Purge Control Solenoid – Check continuity at the purge control solenoid connector pins after removing the plug from the harness using the DVOM set to the ohms scale. Verify that resistance meets manufacturer specifications. Look for a short to ground using the DVOM with the negative lead attached to a known good ground and the positive lead on each of the terminal pins of the purge control valve solenoid. Resistance should be very high or above the limit (OL). If very low resistance is detected, suspect the purge control valve solenoid is shorted to ground and replace it with a known good unit.

PCM/ECM Malfunction – Since EVAP is only activated under certain driving conditions, it will be necessary to monitor EVAP control operation using a capable advanced scan tool and perform a road test under the required driving conditions to activate the EVAP system. Some advanced scan tools have an internal test to manually activate the EVAP system. Verify that the PCM/ECM is commanding the EVAP system. If the system is operating correctly, it will be necessary to probe the PCM/ECM wiring harness connector using a graphing multimeter or oscilloscope with a duty cycle function, with the positive lead on the purge control valve pin and the negative lead connected to a known good ground source. The duty cycle should match what is commanded by the PCM/ECM during EVAP operation. If no duty cycle is present, the PCM/ECM may be faulty.

Other EVAP DTCs: P0440 – P0441 – P0442 – P0443 – P0444 – P0446 – P0447 – P0448 – P0449 – P0452 – P0453 – P0455 – P0456

What does it mean?

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This diagnostic code (DTC) is a generic OBD-II powertrain code. It is considered generic because it applies to all makes and models of vehicles (1996 and newer), although specific repair steps may vary by model.

The Evap purge valve has only one purpose. It closes to seal the vent so that the EVAP system can pressurize and ensure there are no leaks. The Evap purge valve is typically powered by a 12 V battery voltage with the ignition on.

The ECM driver controls the ground, and when grounded, it activates the valve (closing it). If the ECM detects a short to ground and open, or a short to battery voltage on the control circuit, P0446 will be set. The code may also refer to the ECM detecting that the EVAP system is unable to achieve or maintain vacuum during the test.

Symptoms

There will be no obvious symptoms for the driver, other than the illumination of the Malfunction Indicator Lamp (MIL).

Causes

A P0446 code could mean that one or more of the following events have occurred:

Faulty vent valve
Open, short, or excessive resistance in the vent valve control circuit
Obstruction of the purge valve
Faulty PCM

Possible Solutions

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With an OBD-II P0446 fault code, here are some things to try:

Replace the vent valve
Repair open, short, or resistance issues in the control circuit
Repair an open, shorted, or resistance issue in the power circuit
Replace PCM

Other EVAP DTCs: P0440 – P0441 – P0442 – P0443 – P0444 – P0445 – P0447 – P0448 – P0449 – P0452 – P0453 – P0455 – P0456

What does it mean?

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The powertrain control module (PCM) detected an open circuit in the circuit that controls the vent valve or the vapor solenoid for the evaporative emission systems.

When fuel is in the tank, it emits fuel vapor, while the vent line opens and allows the vapors to flow into the engine intake manifold, a charcoal canister, or into the atmosphere, depending on the vehicle. This purge valve is part of the simple yet complicated evaporative emissions system.

Symptoms

Symptoms of a DTC P0447 will include the malfunction indicator light (MIL) illuminating; you probably won’t notice any other symptoms.

Causes

Potential causes may include:

Faulty vent valve
Wiring/circuit issue
PCM fault

Possible Solutions

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Here are some steps to follow to diagnose and repair this fault code:

Check your fuses; there may be a fuse that powers the vent solenoid.

Look for a chafed or rubbed wiring harness. Check both wires to see if they are open to each other, to ground, or to power.

Visually inspect the vent valve for cracks or damage.

Trace the wires to and from the PCM and check continuity using a digital voltmeter (DVOM).

If you have access to an advanced-level scan tool, activate the valve while reading the power and ground at the connector or simply use a test light wired to both terminals; it will light up if the power and ground are OK.

Using a DVOM, check the resistance of the vent; in most cases, the resistance reading should be low—refer to the manufacturer’s specifications or compare it to a new one. A value that is too high or too low indicates a faulty coil inside the valve, meaning a replacement is necessary. This code seems to be common on Dodge, Chrysler, and Jeep products. In these cases, the vent valve was faulty. With GM products (especially trucks), GM released an updated valve set.

Finally, remove the valve; you may be able to access the pivot inside, and it might just be sticking due to fuel residue. Clean it and retest.

Other EVAP DTCs: P0440 – P0441 – P0442 – P0443 – P0444 – P0445 – P0446 – P0448 – P0449 – P0452 – P0453 – P0455 – P0456

What does it mean?

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This code is a generic powertrain code. It is considered generic because it applies to all makes and models of vehicles (1996 and newer), although specific repair steps may vary by model.

The Powertrain Control Module (PCM) has detected that the circuit is shorted together that controls the vent valve or solenoid for the vapor of the evaporative emission systems. In this case, the code will also be triggered when the valve is stuck closed.

When fuel is in the tank, it emits fuel vapor, while the vent line opens and allows the vapors to flow into the engine intake manifold, a charcoal canister, or into the atmosphere, depending on the vehicle. This purge valve is part of the simple yet complicated evaporative emissions system.

Symptoms

Symptoms of a DTC P0448 will include the illumination of the Malfunction Indicator Light (MIL), you will likely not notice any other symptoms.

Causes

Potential causes may include:

Faulty vent valve
Wiring/circuit issue
PCM fault

Possible Solutions

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Here are some steps to follow to diagnose and repair this fault code:

Check your fuses, there may be a fuse that powers the vent solenoid.

Look for a rubbed or chafed wiring harness. Check both wires to see if they are shorted to each other, to ground, or to power.

Visually inspect the vent valve for cracks or damage.

Trace the wires to and from the PCM and check for continuity using a digital volt-ohm meter (DVOM).

If you have access to an advanced-level scan tool, activate the valve while reading the power and ground at the connector or simply using a test light wired to both terminals, it will light up if power and ground are OK.

Using a DVOM, check the resistance of the vent, in most cases the resistance reading should be low, refer to manufacturer specifications or compare it to a new one. A value too high or too low indicates a faulty coil inside the valve, thus meaning a replacement is necessary. This code seems to be widespread on Dodge, Chrysler, and Jeep products. In these cases, the vent valve was faulty. With GM products (especially trucks), GM released a new updated valve assembly.

Finally, remove the valve, you may be able to access the pivot inside and it might just be sticking due to fuel residue. Clean it and retest.

Other EVAP DTCs: P0440 – P0441 – P0442 – P0443 – P0444 – P0445 – P0446 – P0447 – P0449 – P0452 – P0453 – P0455 – P0456

What does it mean?

This code is a generic powertrain group code. It is considered generic because it applies to all vehicle makes and models (1996 and newer), although specific repair steps may vary by model.

The Powertrain Control Module (PCM) / Engine Control Module (ECM) has detected a malfunction in the circuit that controls the vent for the vapor in the evaporative emission systems.

When fuel is in the tank, it emits fuel vapor, while the vent line opens and allows the vapors to flow into the engine intake manifold, a charcoal canister, or into the atmosphere, depending on the vehicle. This purge valve is part of the simple yet complicated evaporative emissions system.

Symptoms

Symptoms of a DTC P0449 will include the illumination of the Malfunction Indicator Light (MIL); you will likely not notice any other symptoms.

Potential causes may include:

• Faulty vent valve
• Wire/circuit issue
• PCM/ECM fault

Possible Solutions

Here are some steps to diagnose and repair this fault code:

Check your fuses; there may be a fuse that powers the vent solenoid.

Look for a chafed or rubbed wiring harness. Check both wires to see if they are shorted to each other, to ground, or to power.

Visually inspect the vent valve for cracks or damage.

Trace the wires to and from the PCM/ECM and check for continuity using a digital volt-ohm meter (DVOM).

If you have access to an advanced-level scan tool, activate the valve while reading the power and ground at the connector, or simply use a test light wired to both terminals; it will light up if power and ground are OK.

Using a DVOM, check the resistance of the vent; in most cases, the resistance reading should be low. Refer to the manufacturer’s specifications or compare it to a new one. A value that is too high or too low indicates a faulty coil inside the valve, meaning replacement is necessary. This code appears to be common on Dodge, Chrysler, and Jeep products. In these cases, the vent valve was faulty. With GM products (especially trucks), GM has released an updated valve assembly.

Finally, remove the valve; you may be able to access the pivot inside, and it might just be sticking due to fuel residue. Clean it and retest.

Other EVAP DTCs: P0440 – P0441 – P0442 – P0443 – P0444 – P0445 – P0446 – P0447 – P0448 – P0452 – P0453 – P0455 – P0456

What does it mean?

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This is a generic powertrain diagnostic trouble code (DTC), meaning it covers all makes/models from 1996 onward. However, specific troubleshooting steps vary by vehicle.

The On-Board Diagnostic (OBD) trouble code P044A is a generic code related to an issue in the Exhaust Gas Recirculation (EGR) valve’s electrical circuit “C”.

The purpose of the EGR valve is to introduce a regulated amount of exhaust gas into the intake manifold. The goal is to keep cylinder head temperatures below 2500°F. Oxygen nitrates (Nox) form when temperatures exceed 2500°F. Nox is responsible for smog and air pollution.

The control computer, either the Powertrain Control Module (PCM) or the Engine Control Module (ECM), has detected an abnormally low, high, or non-existent signal voltage.
EGR Operating Principles

The P044A trouble code refers to the same issue across all vehicles; however, there are many types of EGR systems, sensors, and activation methods. The only similarity is that they all vent exhaust gases into the intake manifold to cool cylinder head temperatures.

Introducing spent exhaust gases into the engine at the wrong time reduces power and causes rough idling or stalling. With this in mind, the computer programming only opens the EGR when the engine speed is above 2000 RPM and closes it under load.

Related EGR “C” sensor fault codes:

P044B Exhaust Gas Recirculation Sensor “C” Circuit Range/Performance
P044C Exhaust Gas Recirculation Sensor “C” Circuit Low
P044D Exhaust Gas Recirculation Sensor “C” Circuit High
P044E Exhaust Gas Recirculation Sensor “C” Circuit Intermittent/Erratic

Symptoms

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Symptoms depend on the EGR pintle’s position at the time of failure.

The service engine soon light will illuminate, and the OBD code P044A will be set. Additionally, a second code related to EGR sensor failure may be set. Code P044C relates to low sensor voltage, and P044D relates to a high voltage situation.
If the EGR pintle is stuck partially open, the vehicle may not idle well or may stall.
Knocking sounds may be heard under load or at high RPM.
No symptoms at all.

Potential Causes

Faulty EGR “C” sensor
Defect in the sensor wiring harness
EGR pintle stuck in the closed position, with carbon buildup preventing it from opening
Lack of vacuum at the EGR solenoid
Faulty EGR solenoid
Faulty EGR position sensor
Faulty EGR differential pressure feedback sensor.

Repair Procedures

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All EGR valves have one thing in common: they recirculate exhaust from the exhaust system to the intake manifold. Beyond that, they differ in their methods of regulating the pintle’s opening and detecting its position.

The following repair procedures represent the most common issues responsible for the majority of EGR system failures. Wiring harness or sensor failures require a service manual to determine the appropriate wire identification and diagnostic procedures.

Keep in mind that wiring differs between manufacturers, and computers do not respond well if the wrong wire is probed. If you probe the wrong wire and send excessive voltage through the computer’s sensor input terminal, the computer may be fried.

Similarly, if the wrong connector is unplugged, the computer could lose its programming, requiring the vehicle to be restarted only after the dealer reprograms the computer.

Code P044A indicates a malfunction in circuit “B”, so check the EGR sensor connector for corrosion, bent or pushed terminals, or loose connections. Clean any corrosion and reinstall the connector.
Remove the electrical connector and take out the EGR. Check for carbon buildup in the EGR’s intake and exhaust passages. Clean any carbon deposits as necessary so the pintle moves up and down smoothly.
Check the vacuum line from the EGR to the solenoid and replace it if defects are found.
Inspect the solenoid’s electrical connector for corrosion or defects.
If the vehicle is a Ford, follow the two vacuum hoses from the EGR to the Differential Pressure Feedback EGR (DPFE) sensor at the rear of the manifold.
Check for corrosion in both pressure hoses. Experience shows that these hoses can become clogged with exhaust carbon. Use a small pocket screwdriver or equivalent to clean the hoses of corrosion, and the sensor should resume functioning.

If the most common tests do not resolve the issue, a service manual is needed to continue testing the wiring circuits. The best solution is to take the vehicle to a service center with the appropriate diagnostic equipment. They can quickly identify and repair this type of problem.

🔍 Meaning

• Generic OBD-II code related to the “C” electrical circuit of the EGR (Exhaust Gas Recirculation) system.

• The PCM/ECM detects an abnormal electrical signal (voltage too low, too high, or absent).

• Note: The “C” designation varies by manufacturer (refer to the specific manual).

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⚙️ EGR Function

• Purpose: To inject exhaust gases into the intake manifold to:

  • Reduce combustion temperatures below 1300°C (prevent NOx formation, a pollutant responsible for smog).

  • Activates only at high RPM (> 2000 RPM) to avoid power loss or stalling.

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⚠️ Symptoms

• Check Engine Light (MIL) illuminated ⚠️.

• Frequent associated codes:

  • P044C (low voltage) / P044D (high voltage) / P044E (intermittent signal).

• Mechanical issues:

  • Stalling or rough idle (if valve stuck open).

  • Knocking during acceleration (if valve stuck closed).

• Special case: No observable symptoms.

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🔧 Possible Causes

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🛠️ Repair Procedures

1. Quick checks (no specialized tools):

• Inspect EGR connectors:

  • Clean corrosion, straighten bent pins.

• Check vacuum hoses:

  • Replace if cracked or detached (especially between solenoid and EGR valve).

• Clean EGR valve:

  • Remove → Clear carbon obstructing passages.

2. Specific case (Ford):

• Locate the DPFE sensor (rear of intake manifold).

• Clean the 2 rubber hoses connected to the exhaust with a fine tool.

3. Advanced diagnostics (requires equipment):

⚠️ Warning:

• Never probe a circuit without an accurate diagram (risk of PCM damage).

• Avoid disconnecting random connectors (may erase PCM programming).

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💡 Final Recommendations

• Temporary solution: EGR cleaning resolves 50% of carbon-related cases.

• Common mistakes:

  • Neglecting DPFE hoses (Ford).

  • Forgetting to check vacuum circuit integrity.

• If unsuccessful:

  🔧 Refer to a professional equipped with OEM diagnostic tools (e.g., Ford IDS, GM Tech2).

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ℹ️ Note: This code is often accompanied by P044A (general “C” circuit fault) – their diagnosis is similar.

What does it mean?

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This code is a generic powertrain code. It is considered generic because it applies to all makes and models of vehicles (1996 and newer), although specific repair steps may vary slightly by model.

There are different EGR (Exhaust Gas Recirculation) system designs, but they all function similarly. The EGR valve is a PCM (Powertrain Control Module) controlled valve that allows measured amounts of exhaust gas to return to the cylinders to be burned with the air/fuel mixture. Since exhaust gas is an inert gas that displaces oxygen, reintroducing it into the cylinder can lower combustion temperatures, which helps improve NOx (Nitrogen Oxides) emissions.

The EGR is not needed during cold starts or at idle. The EGR is activated under certain conditions like startup or idle. The EGR is controlled in specific conditions such as partial acceleration or deceleration depending on engine temperature and load, etc. Exhaust gases are supplied to the EGR valve from an exhaust pipe, or the EGR valve may be mounted directly in the exhaust manifold. When needed, the valve is turned “on,” allowing gases to flow into the cylinders. Some systems divert exhaust gases directly into the cylinders, while others simply inject them into the intake manifold where they are then drawn into the cylinders.

Some EGR systems are quite simple, while others are a bit more complex. Electrically controlled EGR valves are directly controlled by the PCM. A wiring harness plugs into the valve itself and is controlled by the PCM as needed. These may have 4 or 5 wires. Usually, 1 or 2 12-volt ignition power grounds, a 5-volt reference circuit, and a feedback circuit. Other systems are vacuum-controlled. These are fairly simple. The PCM controls a vacuum solenoid that, when activated, allows vacuum to move to the EGR valve and open it. There should also be an electrical connector on this type of EGR valve for the feedback circuit. The EGR system feedback circuit allows the PCM to see if the EGR valve pintle is actually moving as it should.

If the EGR “C” feedback circuit detects that the voltage is abnormally low, or its position is lower than commanded, P044C may be set. Refer to a vehicle-specific repair manual for the location of your “C” sensor.

Related EGR “C” Sensor Fault Codes:

• P044A Exhaust Gas Recirculation “C” Sensor Circuit
• P044B Exhaust Gas Recirculation “C” Sensor Circuit Range/Performance
• P044D Exhaust Gas Recirculation “C” Sensor Circuit High
• P044E Exhaust Gas Recirculation “C” Sensor Circuit Intermittent/Erratic

Symptoms

Symptoms of a P044C DTC may include:

• MIL (Malfunction Indicator Lamp) illumination

Causes

Potential causes of a P044C code include:

• Short to ground in the EGR signal or reference circuits
• Short to voltage in the ground or EGR signal circuits
• Faulty EGR valve
• Bad PCM wiring issues due to chafing or loose terminals

Possible Solutions

If you have access to a scan tool, you can command the EGR valve. If it responds and the feedback indicates the valve is moving correctly, the problem may be intermittent. Sometimes in cold weather, moisture can freeze in the valve and cause it to stick. Once the vehicle warms up, the issue may go away. Carbon or other debris can lodge in a valve, which can also cause it to stick.

If the EGR valve does not respond to your commands with the scan tool, unplug the EGR harness connector. Turn the key to the on position, engine off (KOEO). Using a voltmeter, check for 5 volts on the EGR valve reference wire. If there is no 5 volts, is there any voltage at all? If there is 12 volts, repair the short to voltage in the 5-volt reference circuit. If there is no voltage, connect a test light to battery voltage and probe the 5-volt reference wire. If the test light illuminates, the 5-volt reference circuit is shorted to ground. Repair as necessary. If the test light does not illuminate, check for an open in the 5-volt reference circuit. Repair as necessary.

If there is no apparent issue and there is no 5-volt reference, the PCM may be at fault, but other codes will likely be present. If 5 volts are present on the reference circuit, connect the 5 volts to the EGR signal circuit. Now, the EGR position on the scan tool should read 100%. If it does not, connect the test light to battery voltage and probe the EGR signal circuit. If it lights up, the signal circuit is shorted to ground. Repair as necessary. If the light does not illuminate, look for an open in the EGR signal circuit. Repair as necessary.

If, after connecting the 5-volt reference circuit to the EGR signal circuit, the scan tool EGR position reads 100 percent, check the terminal voltage at the EGR valve connector. If the wiring is correct, replace the EGR valve.