P20BA
PPowertrainReductant (AdBlue) Heater A Control Circuit Performance
What does this code mean?
Severity : MediumP20BA indicates a performance problem in the control circuit of reductant heater A, the AdBlue/DEF heater. The circuit is not open, but the ECU finds that the heater does not behave as expected, such as abnormal current or temperature not rising enough. AdBlue may then stay frozen in cold weather.
Symptoms
- AdBlue or check engine light on.
- Warning message with a countdown before engine start is restricted.
- AdBlue dosing problems in cold weather.
- No noticeable symptom in mild weather.
Possible causes
- Degraded heating element with out-of-range resistance.
- Poor contact or high resistance at the connector.
- Low supply voltage, weak battery or faulty relay.
- Faulty AdBlue temperature sensor.
- Damaged wiring.
Diagnosis and repair
- Check battery condition and heater supply voltage.
- Inspect the connector and wiring for corrosion.
- Measure heating element resistance and check the temperature sensor.
- Replace the heater or affected module if values are out of range.
- Clear the code and test the heater with a diagnostic tool.
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Code
P20BA
Category
Powertrain
Prefix
P
Standard
OBD-II / SAE J2012