P204D Fault Code

Reductant Pressure Sensor Circuit High

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

The P204D fault code indicates a problem with the reductant pressure sensor circuit, which is responsible for monitoring the pressure of the diesel exhaust fluid (DEF) in vehicles equipped with selective catalytic reduction (SCR) systems. This code signals that the sensor has detected a pressure reading that is higher than expected, which can lead to issues with emissions control and overall vehicle performance.

• Importance of Reductant Pressure Sensor: The sensor ensures accurate dosing of DEF to reduce nitrogen oxides (NOx) in the exhaust.
• Potential Impacts: A malfunctioning sensor can result in poor fuel economy, increased emissions, and engine performance issues.

What are the symptoms of the P204D code?

When the P204D code is triggered, you may observe the following symptoms:

• Check Engine Light: The check engine light on the dashboard will illuminate.
• Reduced Engine Performance: You may experience a reduction in engine power, acceleration delays, or difficulty starting.
• Increased Emissions: The vehicle may produce higher levels of emissions, which can affect compliance with environmental regulations.
• AdBlue Warning: In some vehicles, warnings regarding AdBlue fluid levels or quality may appear.

What causes the P204D code?

Several factors can lead to the P204D fault code activation, including:

• Malfunctioning reductant pressure sensor.
• Wiring issues or an open circuit in the sensor harness.
• Corrosion or moisture ingress in the electrical connections.
• Defective engine control module (ECM) or issues with related components in the SCR system.

How to fix P204D?

To resolve the P204D fault code, the following steps are typically recommended:

• Diagnostic Check: Use a diagnostic scan tool to confirm the error code and check for any related codes.
• Inspect Wiring and Connections: Examine the reductant pressure sensor wiring for any signs of damage, corrosion, or disconnections, and repair as necessary.
• Test the Sensor: If the wiring appears intact, test the sensor to ensure it operates within the manufacturer’s specifications. If faulty, replace the sensor.
• Reset the ECU: After repairs, clear the fault codes from the ECU and test drive the vehicle to verify that the issue is resolved. If the code reappears, further diagnosis may be needed.