P22A4NOx Sensor Heater Control Circuit Low (Bank 1 Sensor 2)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P22A4 means the heater control line of the rear NOx sensor on bank 1 has a short to ground, so the sensor module can no longer drive the heater as commanded. GM documents it on the 3.0L LZ0 as a ground short on the heater control pin, judged once dew point is reached and sensor supply exceeds 9.9 V, 80 failures in 160 samples, Type B after two trips. Its 2017 small diesels watch the H+ supply pin of the Gen 3.0 sensor instead, 20 failures in 40 samples. Volvo and Mack count P22A4 among codes that indicate a damaged outlet sensor, and GM bulletin 24-NA-094 adds it to an LZ0 software update for 2024 Silverado and Sierra 1500. Expect the MIL after two trips and no downstream NOx data. P22A3 is the open circuit, P22A5 a short to voltage, P2206 the front sensor.
- What you may notice
- Malfunction indicator lamp on after two trips
- Outlet NOx sensor stays not ready
- SCR warning on the display
- Likely causes
- LikelyHeater element or probe lead shorted to ground inside the sensor
- PossibleProbe lead insulation chafed against the exhaust or body
- RareSoftware anomaly (GM 3.0L LZ0 2024, bulletin 24-NA-094)
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €150 – €1,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.