OBD-II code · Powertrain (generic, extended)
P204A Reductant Pressure Sensor Circuit
A general electrical fault is reported on the DEF system pressure sensor — used to verify pump priming, line pressure, and to detect leaks via pressure-decay tests.
Is it safe to drive with P204A?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySensor failed
- PossibleHarness 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
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.7–2.5 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Pressure Sensor, Reductant Supply Line
Related codes
- P2047Reductant Injection Valve Circuit/Open (Bank 1 Unit 1)
- P2048Reductant Injection Valve Circuit Low (Bank 1 Unit 1)
- P2049Reductant Injection Valve Circuit High (Bank 1 Unit 1)
- P204BReductant Pressure Sensor Circuit Range/Performance
- P204CReductant Pressure Sensor Circuit Low
- P204DReductant Pressure Sensor Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.