OBD-II code · Powertrain (generic, extended)
P20AD Reductant Metering Unit Temperature Sensor Circuit Range/Performance
Metering unit temperature sensor in range but fails plausibility — slow response or stuck reading. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P20AD?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelySensor drift
- Less likelySensor element aged beyond calibration window
- Less likelySensor mounting loose - signal damping
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–4 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Metering Unit
Related codes
- P20ACReductant Metering Unit Temperature Sensor Circuit
- P20AAReductant Injection Air Pressure Control Valve Stuck Open
- P20ABReductant Injection Air Pressure Control Valve Stuck Closed
- P20AEReductant Metering Unit Temperature Sensor Circuit Low
- P20AFReductant Metering Unit Temperature Sensor Circuit High
- P20B0Reductant Metering Unit Temperature Sensor Circuit Intermittent/Erratic
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.