Powertrain
generic / SAE
P21AD
Reductant Level Sensor C Circuit
A general electrical fault is reported on DEF level sensor C — open, shorted, or out of plausibility. Some tanks use multiple level senders to cover irregular tank shapes; this is the primary one.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number1 / AD
Possible causes
- Sender failed high
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Inspection / repair
- Difficulty: hard
- DIY: shop recommended
- Estimated cost: 120–800 €
- Estimated time: 1–4 h
- Component: reductant level sensor
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012