Severity of Code P204E

Level: Critical 🔴

• Immediate Impact: The SCR (Selective Catalytic Reduction) system may be deactivated, leading to increased pollutant emissions (NOx) and a risk of catalyst failure.
• Long-term Risks:
• Damage to the SCR catalyst (high replacement cost: €1,000 to €3,000).
• Overloading of the particulate filter (DPF) due to an unbalanced air-fuel mixture.
• The vehicle may enter limp mode (power limitation, reduced speed).

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Common Symptoms of P204E

• 🚨 Check Engine Light (MIL) or SCR warning light illuminated.
• 🔥 Black or bluish smoke from the exhaust (incomplete combustion).
• 📉 Decreased engine performance (slow acceleration, power loss).
• ⛽ Increased fuel consumption (up to 20%).
• ⚠️ Related Codes: P20EE, P204F, or P2201 (SCR/AdBlue® issues).

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Main Causes of P204E

1. Faulty Reducer Pressure Sensor:

• Incorrect signal due to internal failure or contamination by urea (DEF).

1. Electrical Issues:

• Short circuit or open circuit in the sensor wiring.
• Oxidized or disconnected connectors (exposure to moisture).

1. PCM/SCR Controller Failure:

• Outdated software or calibration error.

1. Faulty Reducer Pump:

• Internal leak or insufficient pressure (related to AdBlue®).

1. Other Causes:

• Low level or poor quality AdBlue®.
• Clogged or damaged SCR injector.

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Detailed Diagnostic Procedure

Required Tools

• Advanced OBD2 scanner (e.g., Delphi, Autel).
• Digital multimeter (DVOM).
• Vehicle-specific technical documentation (wiring diagrams, test procedures).

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Key Steps

1. Check for TSBs (Technical Service Bulletins):

• Look for software updates or recalls related to the SCR system for your model.

1. Code and Live Data Analysis:

• Use the scanner to:
  • Read all stored codes (P204E + related codes).
  • Monitor reducer pressure (compare to manufacturer specifications).
  • Check SCR temperature and AdBlue® flow rate.

1. Pressure Sensor Test:

• Measure the sensor’s resistance and voltage (reference: 0.5–4.5 V depending on pressure).
• Compare with factory values. If out of specifications ➔ replacement required.

1. Electrical Circuit Inspection:

• Test for continuity and absence of short circuits between the sensor and PCM.
• Check the sensor’s power supply (+5V) and ground.

1. SCR Pump and Injector Check:

• Test pump pressure with a pressure gauge (if applicable).
• Inspect the injector for crystalline deposits (clean with a specific kit).

1. Repair Validation:

• Clear codes and perform a drive cycle to check for P204E reappearance.

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Recommended Solutions

• Replacement of the pressure sensor: €150 to €400 (part + labor).
• Cleaning of AdBlue® circuits: Use a certified cleaning kit.
• PCM update: Contact a dealership for reprogramming.
• Replacement of the SCR pump: High cost (€800 to €2,000).

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Important Considerations

• Use only ISO 22241 certified AdBlue® (non-compliant products damage the system).
• Avoid driving with code P204E: Risk of significant additional costs (e.g., SCR catalyst replacement).

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This approach ensures accurate diagnosis and avoids unnecessary repairs. Always consult the manufacturer’s technical guides for exact specifications.

How Serious Is This DTC

A stored P204F code should be considered serious and addressed as soon as possible. The SCR system may be disabled because of this. Catalyst damage can occur if the conditions that contributed to the code being stored are not rectified in a timely manner.

What Are Some of the Symptoms of the Code?

Symptoms of a P204F trouble code may include:

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

What Are Some Common Causes of the Code?

Causes of this code may include:

• Faulty reductant pressure sensor
• Faulty reductant system injector
• Incorrect or inadequate DEF
• Open or shorted circuits in the reductant system
• Faulty SCR controller/PCM or programming error

What Are the P204F Troubleshooting Steps?

A diagnostic scanner, digital volt/ohmmeter (DVOM), and vehicle-specific diagnostic information source will be needed to diagnose a P204F 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 pressure sensor according to manufacturer specifications. Components that do not test within allowable parameters should be considered faulty.

Step 2

If the actual reductant system pressure meets specifications, the P204F code persists, and the sensors are operational, use the DVOM to test the input and output signal circuits between the SCR system sensors and the PCM/SCR controller. Disconnect all controllers before using the DVOM for testing.

Reductant system performance codes are often attributed to low or incorrect DEF

How serious is this DTC?

A stored P2050 code should be considered serious and addressed as soon as possible. The SCR system could 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 P2050 trouble code may include:

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

What are some common causes of the code?

Causes of this code may include:

• Faulty reductant injector valve
• Open or shorted circuits in the reductant injector valve control
• Insufficient DEF in the tank
• Faulty SCR controller/PCM or programming error

What are the troubleshooting steps for P2050?

You will need access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information to diagnose a P2050 code.

If you can find a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as the engine size, stored code(s), and presented symptoms, it could provide useful diagnostic information.

You’ll want to start your diagnosis with a visual inspection of the reductant heater system harnesses and connectors. Burned or damaged wiring and/or connectors should be repaired or replaced before continuing.

Proceed by hooking up the scanner to the vehicle’s diagnostic connector and retrieving all stored codes and relevant freeze frame data. Note this information before clearing the codes and test drive the vehicle until the PCM enters readiness mode or the code resets.

The code is intermittent and may be much more difficult to diagnose (for the time being) if the PCM enters readiness mode. 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 resets, consult your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, as well as component testing procedures and specifications. This information will be needed to complete the next step of your diagnosis.

Use the DVOM to test the SCR control system power supply. Test fuses with the circuit loaded to avoid misdiagnosis. If proper power and ground circuits are detected, use the scanner to activate the reductant injector valve (solenoid) and test the output control circuit voltage. If voltage is insufficient, suspect the controller is faulty or has encountered a programming error.

If the voltage output circuit is within parameters, use the DVOM to test the reductant injector valve in question. If the valve does not meet manufacturer specifications, suspect it has failed.

The reductant injector valve is actually a solenoid injector that sprays reductant fluid into the exhaust

How serious is this DTC?

A stored P2051 code should be considered serious and addressed as soon as possible. The SCR system could 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 P2051 trouble code may include:

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

What are some common causes of the code?

Causes

of this code may include:

• Faulty reductant injector valve
• Open or shorted circuits in the reductant injector valve control
• Insufficient DEF in the tank
• Faulty SCR controller/PCM or programming error

What are the troubleshooting steps for P2051?

You will need access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information to diagnose a P2051 code.

If you can find a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as the engine size, stored code(s), and presented symptoms, it could provide useful diagnostic information.

You’ll want to start your diagnosis with a visual inspection of the reductant heater system harnesses and connectors. Burned or damaged wiring and/or connectors should be repaired or replaced before continuing.

Proceed by hooking up the scanner to the vehicle’s diagnostic connector and retrieving all stored codes and relevant freeze frame data. Note this information before clearing the codes and test drive the vehicle until the PCM enters readiness mode or the code resets.

The code is intermittent and may be much harder to diagnose (for now), if the PCM enters readiness mode. 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 resets, consult your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, as well as component testing procedures and specifications. This information will be needed to complete the next step of your diagnosis.

Use the DVOM to test the SCR control system’s power supply. Test fuses with the circuit loaded to avoid misdiagnosis. If the proper power and ground circuits are detected, use the scanner to activate the reductant injector valve (solenoid) and test the output control circuit voltage. If the voltage is insufficient, suspect the controller is faulty or has encountered a programming error.

If the voltage output circuit is within parameters, use the DVOM to test the reductant injector valve in question. If the valve does not meet manufacturer specifications, suspect it has failed.

The reductant injector valve is actually a solenoid injector that sprays reductant fluid into the exhaust

How Serious Is This DTC?

A stored P2052 code should be considered serious and addressed as soon as possible. The SCR system could 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 P2052 trouble code may include:

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

What Are Some Common Causes of the Code?

Causes of this code may include:

• Faulty reductant injector valve
• Open or shorted circuits in the reductant injector valve control
• Insufficient DEF in the tank
• Faulty SCR controller/PCM or programming error

What Are the P2052 Troubleshooting Steps?

You will need access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information to diagnose a P2052 code.

If you can find a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as the engine size, stored code(s), and presented symptoms, it could provide helpful diagnostic information.

You’ll want to start your diagnosis with a visual inspection of the reductant heater system harnesses and connectors. Burned or damaged wiring and/or connectors should be repaired or replaced before continuing.

Proceed by connecting the scanner to the vehicle’s diagnostic connector and retrieving all stored codes and relevant freeze frame data. Note this information before clearing the codes and test drive the vehicle until the PCM enters readiness mode or the code resets.

The code is intermittent and may be much more difficult to diagnose (for the time being) if the PCM enters readiness mode. 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 resets, consult your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, as well as component testing procedures and specifications. This information will be needed to complete the next step of your diagnosis.

Use the DVOM to test the SCR control system’s power supply. Test fuses with the circuit loaded to avoid misdiagnosis. If proper power and ground circuits are detected, use the scanner to activate the reductant injector valve (solenoid) and test the output control circuit voltage. If voltage is insufficient, suspect a faulty controller or a programming error.

If the output voltage circuit is within parameters, use the DVOM to test the reductant injector valve in question. If the valve does not meet manufacturer specifications, suspect it has failed.

The reductant injector valve is actually a solenoid injector that sprays reductant fluid into the exhaust

How serious is this DTC?

A stored P2053 code should be considered serious and addressed as quickly as possible. The SCR system could 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 P2053 trouble code may include:

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

What are some common causes of the code?

Causes of this code may include:

• Faulty reductant injector valve
• Open or shorted circuits in the reductant injector valve control
• Insufficient DEF in the tank
• Faulty SCR controller/PCM or programming error

What are the troubleshooting steps for P2053?

You will need access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information to diagnose a P2053 code.

If you can find a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as the engine size, stored code(s), and presented symptoms, it could provide helpful diagnostic information.

You’ll want to start your diagnosis with a visual inspection of the reductant heater system harnesses and connectors. Burned or damaged wiring and/or connectors should be repaired or replaced before continuing.

Proceed by hooking up the scanner to the vehicle’s diagnostic connector and retrieving all stored codes and relevant freeze frame data. Note this information before clearing the codes and test drive the vehicle until the PCM enters readiness mode or the code resets.

The code is intermittent and may be much more difficult to diagnose (for the time being) if the PCM enters readiness mode. 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 resets, consult your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, as well as component testing procedures and specifications. This information will be needed to complete the next step of your diagnosis.

Use the DVOM to test the SCR control system power supply. Test fuses with the circuit loaded to avoid misdiagnosis. If proper power and ground circuits are detected, use the scanner to activate the reductant injector valve (solenoid) and test the output control circuit voltage. If voltage is insufficient, suspect the controller is faulty or has encountered a programming error.

If the voltage output circuit is within parameters, use the DVOM to test the reductant injector valve in question. If the valve does not meet manufacturer specifications, suspect it has failed.

The reductant injector valve is actually a solenoid injector that sprays reductant fluid into the exhaust

How serious is this DTC?

A stored P2054 code should be considered serious and addressed as quickly as possible. The SCR system could 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 P2054 trouble code may include:

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

What are some common causes of the code?

Causes of this code may include:

• Faulty reductant injection valve
• Open or shorted circuits in the reductant injection valve control
• Insufficient DEF in the tank
• Faulty SCR controller/PCM or programming error

What are the troubleshooting steps for P2054?

You will need access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information to diagnose a P2054 code.

If you can find a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as the engine size, stored code(s), and symptoms presented, it could provide helpful diagnostic information.

You’ll want to start your diagnosis with a visual inspection of the reductant heater system harnesses and connectors. Burned or damaged wiring and/or connectors should be repaired or replaced before continuing.

Proceed by connecting the scanner to the vehicle’s diagnostic connector and retrieving all stored codes and relevant freeze frame data. Note this information before clearing the codes and test drive the vehicle until the PCM enters readiness mode or the code resets.

The code is intermittent and may be much more difficult to diagnose (for the time being) if the PCM enters readiness mode. 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 resets, consult your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, as well as component testing procedures and specifications. This information will be needed to complete the next step of your diagnosis.

Use the DVOM to test the SCR control system power supply. Test fuses with the circuit loaded to avoid misdiagnosis. If proper power and ground circuits are detected, use the scanner to activate the reductant injector valve (solenoid) and test the output control circuit voltage. If voltage is insufficient, suspect the controller is faulty or has encountered a programming error.

If the voltage output circuit is within parameters, use the DVOM to test the reductant injection valve in question. If the valve does not meet manufacturer specifications, suspect it has failed.

How serious is this DTC?

A stored P2055 code should be considered serious and addressed as soon as possible. The SCR system could 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 symptoms of the code?

Symptoms of a P2055 trouble code may include:

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

What are some common causes of the code?

Causes of this code may include:

• Faulty reductant injection valve
• Open or shorted circuits in the reductant injection valve control
• Insufficient DEF in the tank
• Faulty SCR controller/PCM or programming error

What are the troubleshooting steps for P2055?

You will need access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information to diagnose a P2055 code.

If you can find a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as the engine size, stored code(s), and presented symptoms, it could provide helpful diagnostic information.

You’ll want to start your diagnosis with a visual inspection of the reductant heater system harnesses and connectors. Burned or damaged wiring and/or connectors should be repaired or replaced before continuing.

Proceed by hooking up the scanner to the vehicle’s diagnostic connector and retrieving all stored codes and relevant freeze frame data. Note this information before clearing the codes and test drive the vehicle until the PCM enters readiness mode or the code resets.

The code is intermittent and may be much more difficult to diagnose (for the time being) if the PCM enters readiness mode. 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 resets, consult your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, as well as component testing procedures and specifications. This information will be needed to complete the next step of your diagnosis.

Use the DVOM to test the SCR control system power supply. Test fuses with the circuit loaded to avoid misdiagnosis. If proper power and ground circuits are detected, use the scanner to activate the reductant injector valve (solenoid) and test the output control circuit voltage. If voltage is insufficient, suspect the controller is faulty or encountered a programming error.

If the voltage output circuit is within parameters, use the DVOM to test the reductant injection valve in question. If the valve does not meet manufacturer specifications, suspect it has failed.

The reductant injection valve is actually a solenoid injector that sprays reductant fluid into the exhaust

How serious is this DTC?

A stored P2056 code should be considered serious and addressed as quickly as possible. The SCR system could 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 P2056 trouble code may include:

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

What are some common causes of the code?

Causes

of this code may include:

• Faulty reductant injector valve
• Open or shorted circuits in reductant injector valve control
• Insufficient DEF in tank
• Faulty SCR controller/PCM or programming error

What are the troubleshooting steps for P2056?

You will need access to a diagnostic scanner, digital volt/ohmmeter (DVOM), and vehicle-specific diagnostic information source to diagnose a P2056 code.

If you can find a technical service bulletin (TSB) that matches the vehicle’s year, make and model; plus engine size, stored code/s and presented symptoms, it could provide helpful diagnostic information.

You’ll want to start your diagnosis with a visual inspection of the reductant heater system harnesses and connectors. Burned or damaged wiring and/or connectors should be repaired or replaced before continuing.

Proceed by hooking up the scanner to the vehicle’s diagnostic connector and retrieving all stored codes and relevant freeze frame data. Note this information before clearing the codes and test drive the vehicle until the PCM enters readiness mode or the code resets.

The code is intermittent and may be much harder to diagnose (for the time being), if the PCM enters readiness mode. 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 resets, consult your vehicle information source for diagnostic flow charts, connector pinout diagrams, connector face views, along with component testing procedures and specifications. This information will be needed to complete the next step of your diagnosis.

Use the DVOM to test the SCR control system power supply. Test fuses with the circuit loaded to avoid misdiagnosis. If proper power and ground circuits are detected, use the scanner to activate the reductant injector valve (solenoid) and test the output control circuit voltage. If voltage is insufficient, suspect the controller is faulty or encountered a programming error.

If the voltage output circuit is within parameters, use the DVOM to test the reductant injector valve in question. If the valve doesn’t meet manufacturer specifications, suspect it has failed.

The reductant injector valve is actually a solenoid injector that sprays reductant fluid into the exhaust

How serious is this DTC?

A stored P2057 code should be considered serious and addressed as soon as possible. The SCR system could 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 P2057 trouble code may include:

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

What are some common causes of the code?

Causes of this code may include:

• Faulty reductant injection valve
• Open or shorted circuits in the reductant injection valve control
• Insufficient DEF in the tank
• Faulty SCR controller/PCM or programming error

What are the troubleshooting steps for P2057?

You will need access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information to diagnose a P2057 code.

If you can find a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as the engine size, stored code(s), and presented symptoms, it could provide helpful diagnostic information.

You’ll want to start your diagnosis with a visual inspection of the reductant heater system harnesses and connectors. Burned or damaged wiring and/or connectors should be repaired or replaced before continuing.

Proceed by hooking up the scanner to the vehicle’s diagnostic connector and retrieving all stored codes and relevant freeze frame data. Note this information before clearing the codes and test drive the vehicle until the PCM enters readiness mode or the code resets.

The code is intermittent and may be much more difficult to diagnose (for the time being) if the PCM enters readiness mode. 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 resets, consult your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, as well as component testing procedures and specifications. This information will be needed to complete the next step of your diagnosis.

Use the DVOM to test the SCR control system’s power supply. Test fuses with the circuit loaded to avoid misdiagnosis. If the proper power and ground circuits are detected, use the scanner to activate the reductant injector valve (solenoid) and test the output control circuit voltage. If the voltage is insufficient, suspect that the controller is faulty or has encountered a programming error.

If the voltage output circuit is within parameters, use the DVOM to test the reductant injection valve in question. If the valve does not meet manufacturer specifications, suspect that it has failed.

The reductant injection valve is actually a solenoid injector that sprays reductant fluid into the exhaust