P20AEReductant Metering Unit Temperature Sensor Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P20AE is stored when the signal of the metering unit temperature sensor falls below its valid band. If the sensor is an NTC thermistor, the common design, though no maker confirms it publicly for this part, a low voltage stands for a very high indicated temperature. Typical reasons are then a signal wire chafed through to ground, moisture or DEF crystals bridging the connector pins, or a shorted sensor element. No manufacturer reference names this exact code; CARB merely requires the input to be checked for out-of-range values. The control unit then usually discards the reading and may suspend dosing. The upper counterpart is P20AF, while unclear electrical faults go to P20AC.
- What you may notice
- Warning lamp on immediately after key-on
- Module temperature shown far too hot in live data
- DEF dosing suspended, inducement countdown possible
- Likely causes
- LikelySignal wire shorted to ground (chafing near tank or frame)
- PossibleWater or DEF residue bridging the connector pins
- PossibleSensor element in the metering unit shorted
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €1,800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.