Powertrain, generic (extended)

P23B0 NOx Sensor Circuit Intermittent (Bank 1 Sensor 3)

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P23B0 is meant for a third NOx sensor on bank 1 whose circuit faults come and go instead of staying present, so the status the sensor module reports over CAN keeps toggling between valid and faulty. No manufacturer documents P23B0 publicly, and none publishes a threshold for it; GM's 2025 diesel table, which details several other sensor 3 codes, does not list it. HELLA's workshop guidance on NOx sensors names plug connections and wiring harmed by moisture, grime and road salt and recommends checking supply and bus communication – a good fit for a fault that keeps returning. CARB requires circuit faults on NOx sensors to be detected. P23AC is the steady circuit fault; P2204 and P22A2 are the intermittent codes of sensors 1 and 2. The MIL may go out and come back.

Likely causes

Loose or fretting terminal in a sensor 3 connector
Harness rubbing or flexing near the exhaust, breaking contact under vibration
Moisture entering a connector in wet weather

Symptoms

  • Check engine light that goes out and returns
  • Sensor 3 value drops out briefly in live data

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–900
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

nox sensor b1s3

Related codes

P23ACP23ADP2204P22A2

References: law.cornell.edu, hella.com, ni.com.