P204C: Reductant Pressure Sensor Circuit Low
The P204C code indicates that the reductant (DEF) pressure sensor circuit is reading a voltage lower than the expected range. This sensor monitors the pressure of the diesel exhaust fluid (DEF) in the injection system. A low circuit signal can be caused by a faulty sensor, wiring issues, or a problem with the DEF pump or control module. This condition can lead to incorrect DEF injection, potentially causing increased emissions and triggering the check engine light.
1. Most Common Causes
- Faulty reductant pressure sensor
- Open or shorted wiring in the sensor circuit
- Poor electrical connection at the sensor
- Defective DEF pump or control module
2. Symptoms You Will Notice
- Check engine light illuminated
- Reduced engine performance or limp mode
- Increased diesel exhaust fluid consumption
- Possible failed emissions test
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to verify the code and check for related codes.
Step 2: Inspect the reductant pressure sensor and its wiring for damage, corrosion, or loose connections.
Step 3: Test the sensor's voltage and resistance per manufacturer specifications.
Step 4: If sensor and wiring are okay, test the DEF pump and control module operation.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances with this code, as it can cause reduced engine performance and may lead to increased emissions or limp mode. It's best to diagnose and repair promptly.
How much does it cost to fix?▼
The cost to fix P204C typically ranges from $50 to $150 for diagnosis and sensor replacement, but can be higher if the DEF pump or control module needs replacement.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.