P202A
PPowertrainAdBlue Tank Heater Control Circuit/Open
What does this code mean?
Severity : MediumP202A indicates an open or fault in the reductant tank heater control circuit, the heater that thaws AdBlue/DEF in the tank. It is needed in cold weather, as AdBlue freezes at around minus 11 °C. The ECU detects an electrical problem and can no longer guarantee AdBlue availability when it freezes.
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
- Open AdBlue tank heating element.
- Corroded tank module connector, often exposed to road spray.
- Broken or chafed wiring under the vehicle.
- Faulty heater fuse or relay.
- Less commonly, an SCR control unit fault.
Diagnosis and repair
- Inspect the tank module connector and wiring under the vehicle.
- Check the heater supply fuse and relay.
- Measure heating element resistance against the manufacturer's values.
- Repair the wiring or replace the heater or tank module.
- Clear the code and check operation with a diagnostic tool.
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Code
P202A
Category
Powertrain
Prefix
P
Standard
OBD-II / SAE J2012