P204D: Reductant Pressure Sensor Circuit High
The P204D code indicates that the reductant (DEF) pressure sensor circuit is reporting a voltage higher than the expected range. This sensor monitors the pressure of the diesel exhaust fluid in the injection system. A high circuit signal can be caused by a faulty sensor, wiring issues (short to voltage), 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.
01. Most Common Causes
- Faulty reductant pressure sensor
- Short to voltage in sensor wiring or connector
- Corroded or damaged sensor connector
- Defective DEF pump or control module
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or limp mode
- Increased diesel exhaust fluid consumption
- Possible white smoke from exhaust
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for related codes.
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 shorts to voltage in the sensor circuit by disconnecting the sensor and measuring voltage at the harness connector.
Step 5: If wiring is intact, replace the reductant pressure sensor and clear the code.
04. Commonly Affected Makes
05. 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 performance and may lead to more serious issues. However, you can drive to a repair shop if the vehicle is not in limp mode.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and sensor replacement, but can be higher if wiring repairs or module replacement is needed.