P2043: Reductant Temperature Sensor A Circuit Range/Performance
What to do
Ask whether the tank heater was commanded on and the temperature watched for a response. A sensor stuck cold and a heater that has failed produce the same reading, and in winter the second one stops the system dosing at all.
What this code means
The reductant temperature reading is electrically valid but implausible — most often a value that does not rise when the tank heater is running, or one that never changes at all.
A reading that stays stubbornly cold has two explanations worth separating, and they are not equally cheap. Either the sensor has failed in place, or the tank heater genuinely is not working and the fluid really is that cold. The second matters more in winter, and the cold-soak comparison used elsewhere in the corpus does not settle it here — both possibilities look identical on a cold morning. Commanding the heater and watching whether the reading responds is what separates them.
Likely causes
Start here
- Faulty reductant temperature sensor · moderate
- Faulty reductant tank heater · moderate
Less common
- Corroded or loose connector · easy
- Low reductant level · easy
Symptoms
Components involved
Information, not instruction
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Community experience
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