OBD-II code · Powertrain (generic, extended)
P23AF NOx Sensor Circuit High Bank 1 Sensor 3
Same as P23AC with the signal voltage above the plausible range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P23AF?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySignal shorted to supply
- Less likelyConnector pins corroded - high contact resistance
- Less likelySupply wire pinched against B+ source
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
- 1–1.8 h
- Emissions test
- Likely to fail
- Parts involved
- Nox Sensor B1s3
Related codes
- P23ACNOx Sensor Circuit Bank 1 Sensor 3
- P23ADNOx Sensor Circuit Range or Performance Bank 1 Sensor 3
- P23AENOx Sensor Circuit Low Bank 1 Sensor 3
- P23B0NOx Sensor Circuit Intermittent Bank 1 Sensor 3
- P23B1NOx Sensor Heater Control Circuit Open Bank 1 Sensor 3
- P23B2NOx Sensor Heater Control Circuit Low Bank 1 Sensor 3
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.