P203DReductant Level Sensor A Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P203D is the high-side fault of level sensor A. On the LML Duramax and the 2014 Cruze 2.0D, GM samples level contact 1 1.5 ms after a test pulse: 3.56 to 4.74 V means an open load, above 4.74 V a short to battery, either one for more than 3 s with Type A. GM's 2017 diesel table uses a raw value above 95 (Type B), while the 2025 DEF controller sets P203D when the ultrasonic sensor reports a level beyond its 400 mm measuring range for 6 s. Preliminary bulletin PIP4887B for 2010–2011 Duramax trucks names P203D with P21AB and P21B0 and asks for wiring and terminal checks even on history codes before a new DEF tank. FCA (Ram 6.7L, 2014–2015) and Jaguar (2.0D, overfilled tank reading zero) list P203D as well. Low-side faults are P203C.
- What you may notice
- MIL with Service Exhaust Fluid System or similar message
- DEF gauge missing or showing full permanently
- Speed or restart limit if not repaired
- Likely causes
- LikelyOpen circuit, unplugged or loose tank connector
- PossibleSignal wire shorted to supply or battery voltage
- PossibleOverfilled tank on ultrasonic sensors
- PossibleFailed level sensor or tank assembly
- 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: €60 – €1,300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.