OBD-II code · Powertrain (generic, extended)
P209A Reductant Injection Air Pressure Sensor B Circuit
A general electrical fault is reported on reductant injection air-pressure sensor B — the second air-assist pressure sensor on dual-bank or dual-injector DEF systems.
Is it safe to drive with P209A?
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 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Air Pressure Sensor
Related codes
- P2037Reductant Injection Air Pressure Sensor A Circuit
- P2097Post Catalyst Fuel Trim System Too Rich (Bank 1)
- P2098Post Catalyst Fuel Trim System Too Lean (Bank 2)
- P2099Post Catalyst Fuel Trim System Too Rich (Bank 2)
- P209BReductant Injection Air Pressure Sensor B Circuit Range/Performance
- P209CReductant Injection Air Pressure Sensor B Circuit Low
- P209DReductant Injection Air Pressure Sensor B Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.