Reductant Pressure Sensor Circuit Intermittent/Erratic
The P204E code indicates that the powertrain control module (PCM) has detected an intermittent or erratic signal from the reductant pressure sensor, which monitors the pressure of diesel exhaust fluid (DEF) in the selective catalytic reduction (SCR) system. This can cause improper DEF injection, leading to increased emissions and potential catalyst damage. The issue is often related to wiring, connector problems, or a faulty sensor.
01. Most Common Causes
- Faulty reductant pressure sensor
- Damaged or corroded wiring/connectors in the sensor circuit
- Intermittent short or open in the sensor circuit
- DEF contamination or air in the system
- PCM software or hardware issue (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or power
- Increased DEF consumption or warning messages
- Failed emissions test
- Engine may enter limp mode
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm code P204E and check for related codes.
Step 2: Visually inspect the reductant pressure sensor and its wiring/connector for damage, corrosion, or loose connections.
Step 3: Test the sensor's voltage and ground signals with a multimeter; compare to manufacturer specifications.
Step 4: If wiring is intact, replace the reductant pressure sensor and clear the code.
Step 5: If the code returns, check for DEF system issues like contamination or air in the line.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances. The issue can cause reduced performance, increased emissions, and potential damage to the SCR system. You may experience limp mode.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a sensor replacement if DIY, or $150 to $300 at a shop including labor and diagnostics.