P203EReductant Level Sensor A Circuit Intermittent/Erratic
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P203E stands for a level sensor A signal that keeps dropping out or jumping. FCA explains it best: Ram HD trucks with the 6.7L Cummins (2019–2021) carry an ultrasonic level sensor that needs an air gap above the fluid. Bulletin 18-034-21 and STAR case S2025000001 name an overfilled tank as the main trigger, because the echo no longer returns; residual ice or urea crystals in the focus tube after hard frost do the same. Returned parts were mostly found free of faults. The test only runs with ambient and tank above about 4 °C, so the fix is draining 2 to 3 gallons or thawing the tank, then about 15 min of steady highway driving. Jeep and Ram 3.0L EcoDiesel software updates (18-018-14, 18-018-15) also cover P203E. Steady circuit faults belong to P203C/P203D.
- What you may notice
- MIL and Service DEF message
- DEF gauge jumps or reads 0 % with fluid in the tank
- Warning returns after filling or after a cold night
- Likely causes
- LikelyDEF tank overfilled, no air space for the ultrasonic echo
- LikelyResidual ice or urea crystals covering the sensor
- PossibleIntermittent contact at the tank connector
- RareControl unit software needing an update
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €0 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.