P204B Fault Code

Reductant Pressure Sensor Circuit Range/Performance

• What does that mean?
• Symptoms
• Causes
• Solutions

The P204B fault code indicates an issue with the Reductant Pressure Sensor Circuit. This sensor plays a critical role in monitoring the pressure of the reductant (often diesel exhaust fluid or DEF) that is injected into the exhaust stream to reduce emissions. When this fault code appears, it suggests that the signal from the pressure sensor is outside the expected range, indicating a potential malfunction or performance issue.

What are the symptoms of the P204B code?

Symptoms associated with the P204B fault code may include:

• Warning lights on the dashboard, such as the check engine light
• Reduced engine performance
• Increased emissions leading to potential fines or inspections failures
• The vehicle may enter limp mode to prevent further damage.

What causes the P204B code?

Common causes for the P204B code include:

• Faulty reductant pressure sensor
• Wiring issues such as shorts, opens, or poor connections within the sensor circuit
• Blockages or restrictions in the reductant system
• Defective engine control module (ECM) or software related to reductant management.

How to fix P204B?

To resolve the P204B fault code, a technician should:

• Perform a visual inspection of the reductant pressure sensor and circuit for any obvious damage or disconnections
• Test the sensor for proper operation and replace it if it’s faulty
• Check for any blockages in the reductant system
• If necessary, reset the vehicle's ECM and clear the fault codes before conducting a test drive to ensure the issue is fully resolved.