P21ADReductant Level Sensor C Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P21AD covers the electrical circuit of the third reductant level sensor, so it only exists on tanks with at least three level points. GM's 6.6L Duramax and 2014 Cruze diesel are such cases: the tank electronics test sensors 1 to 3 separately and pass each status to the ECM over CAN. GM uses the specific codes P21AF and P21B0 instead of this summary code. If P21AD shows up together with P21A8 and P203A, a shared supply, ground or the tank connector is far more likely than three failed sensors at once. Since the level information feeds the DEF range and refill warnings, drivers may see a missing or wrong range message besides the MIL. CARB asks for circuit monitoring of such inputs in 13 CCR 1968.2 (f)(15.2.1).
- What you may notice
- Check engine light on
- DEF range message missing or implausible
- Further level sensor codes stored
- Likely causes
- LikelyFault in a supply, ground or connector shared by the level sensors
- PossibleLevel sensor C in the tank assembly failed
- PossibleSensor C signal wire damaged
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.