OBD-II code · Powertrain (generic, extended)
P203A Reductant Level Sensor A Circuit
A general electrical fault is reported on DEF level sensor A — open, shorted, or out of plausibility. Some tanks use multiple level senders to cover irregular tank shapes; this is the primary one.
Is it safe to drive with P203A?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelySender failed — float, swing arm, or rheostat
- PossibleHarness or connector fault
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)
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–4 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Level Sensor, Reductant Tank
Related codes
- P21A8Reductant Level Sensor B Circuit
- P21ADReductant Level Sensor C Circuit
- P2037Reductant Injection Air Pressure Sensor A Circuit
- P2038Reductant Injection Air Pressure Sensor A Circuit Range/Performance
- P2039Reductant Injection Air Pressure Sensor A Circuit Low
- P203BReductant Level Sensor A Circuit Range/Performance
- P203CReductant Level Sensor A Circuit Low
- P203DReductant Level Sensor A Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.