P22A6NOx Sensor Heater Sense Circuit (Bank 1 Sensor 2)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- Besides the heater supply, a NOx sensor has a sense line through which its module measures the resistance of the heated element and so infers its temperature. P22A6 reports an electrical fault on that feedback line of the rear sensor on bank 1. GM's 3.0L LZ0 sets it for an open circuit at the HTemp pin, 80 failures in 160 samples, Type A after one trip; GM notes that the Continental Gen 3.5 sensor debounces electrical faults internally for 1.5 s. The 2017 small diesels use the same open-circuit check with 20 failures in 40 samples, also Type A. Volvo and Mack list P22A6 among codes that call for a new outlet sensor; GM bulletin 24-NA-094 names it Heater Feedback Circuit and covers it with an LZ0 software update. P22A8/P22A9 are shorts, P22A7 plausibility, P2208 the front sensor.
- What you may notice
- Malfunction indicator lamp on after one trip
- Outlet NOx sensor not ready, no downstream value
- SCR warning on the display
- Likely causes
- LikelyOpen heater sense conductor inside the outlet NOx probe or its lead
- PossibleWater or corrosion in the probe connector
- 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.