P20AE code meaning
Reductant Metering Unit Temperature Sensor Circuit Low
Powertrain system Generic code P20xx codes Check engine light
What P20AE means
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.
P20AE at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P20AE
- Warning lamp on immediately after key-on
- Module temperature shown far too hot in live data
- DEF dosing suspended, inducement countdown possible
Common causes of P20AE
- Most 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
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Reductant metering unitReductant metering temp sensor
What each part of P20AE means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 0 | Area: fuel and air metering and auxiliary emission controls. |
| AE | The exact fault in that area. |
What to do next
- Note P20AE and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P20AE
What does P20AE mean?
P20AE means "Reductant Metering Unit Temperature Sensor Circuit Low". P20AE is stored when the signal of the metering unit temperature sensor falls below its valid band. It is a generic code, so it means the same on every make.
Is it safe to drive with P20AE?
Drive gently and only to a workshop. With P20AE the car can go into limp mode (reduced power) to protect itself.
Will P20AE fail an emissions test?
Yes, it can. P20AE is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P20AE to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P20AE clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.