OBD-II code · Powertrain (generic, extended)
P23B1 NOx Sensor Heater Control Circuit Open Bank 1 Sensor 3
The heater control circuit for the NOx sensor on bank 1 sensor 3 is open. Without the heater the sensor cannot reach operating temperature; readings stay invalid.
Is it safe to drive with P23B1?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyOpen in heater control wiring
- Less likelyPin pushed back out of connector body
- Less likelyCracked solder joint inside the module or sensor
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
- 1–2 h
- Emissions test
- Likely to fail
- Parts involved
- Nox Sensor B1s3 Heater
Related codes
- P23AENOx Sensor Circuit Low Bank 1 Sensor 3
- P23AFNOx Sensor Circuit High Bank 1 Sensor 3
- P23B0NOx Sensor Circuit Intermittent Bank 1 Sensor 3
- P23B2NOx Sensor Heater Control Circuit Low Bank 1 Sensor 3
- P23B3NOx Sensor Heater Control Circuit High Bank 1 Sensor 3
- P23B4NOx Sensor Heater Sense Circuit Bank 1 Sensor 3
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.