Reductant Metering Unit Temperature Sensor Circuit Range/Performance
The P20AD code indicates that the reductant metering unit temperature sensor circuit is reporting a value outside the expected range or has a performance issue. This sensor monitors the temperature of the diesel exhaust fluid (DEF) in the metering unit, which is critical for proper injection into the exhaust stream. A faulty sensor or circuit can lead to incorrect DEF dosing, potentially causing increased emissions, reduced fuel economy, and triggering the check engine light.
01. Most Common Causes
- Faulty reductant metering unit temperature sensor
- Open or shorted wiring in the sensor circuit
- Poor electrical connection at the sensor or ECM
- Contaminated or degraded DEF fluid affecting sensor readings
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or power
- Increased fuel consumption
- Possible failed emissions test
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 wiring and connector for damage, corrosion, or loose connections.
Step 3: Test the sensor resistance and compare to manufacturer specifications.
Step 4: Check the DEF fluid level and quality; replace if contaminated.
Step 5: If all else fails, replace the reductant metering unit temperature sensor.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally not recommended to drive long distances with this code, as it can lead to improper DEF dosing, increased emissions, and potential damage to the SCR system. However, short trips may be possible if the vehicle is not in limp mode.
How much does it cost to fix?▼
The cost to fix P20AD typically ranges from $50 to $150, including parts and labor. The sensor itself is relatively inexpensive, but diagnostic time and labor can add to the cost.