Reductant Pressure Sensor Circuit Malfunction
The P204A code indicates a problem with the reductant pressure sensor circuit, which monitors the pressure of diesel exhaust fluid (DEF) in the selective catalytic reduction (SCR) system. This sensor is critical for proper DEF injection to reduce NOx emissions. A fault can cause the engine control module (ECM) to detect an incorrect voltage signal, leading to reduced engine performance or illumination of the check engine light.
01. Most Common Causes
- Faulty reductant pressure sensor
- Open or shorted wiring in the sensor circuit
- Poor electrical connection at the sensor connector
- Corroded or damaged sensor harness
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Increased diesel exhaust fluid consumption
- Failed emissions test
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to retrieve all stored codes and freeze frame data.
Step 2: Visually inspect the reductant pressure sensor and its wiring for damage, corrosion, or loose connections.
Step 3: Test the sensor's voltage signal with a multimeter; compare to manufacturer specifications.
Step 4: Check for continuity and shorts in the sensor circuit between the sensor and ECM.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as it may lead to reduced engine performance and potential damage to the SCR system. Immediate diagnosis is advised.
How much does it cost to fix?▼
Repair costs typically range from $50 to $150 for parts and labor, depending on the cause and vehicle model.