Powertrain
generic / SAE
P23BA
NOx Sensor Heater Sense Circuit Intermittent Bank 1 Sensor 3
Same as P23B4 with intermittent or erratic signal. 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.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number3 / BA
Possible causes
- Intermittent contact at connector high
- Connector with intermittent contact under vibration low
- Harness routed against vibrating component low
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)
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 400–850 €
- Estimated time: 1–2 h
- Component: nox sensor b1s3 heater
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012