P22AANOx Sensor Heater Sense Circuit Intermittent (Bank 1 Sensor 2)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P22AA covers a heater sense line on the rear NOx sensor of bank 1 that fails only now and then. The module uses this line to read the element temperature and keep the heater on target; if the reading drops out or jumps for short moments, the temperature control briefly loses its reference and the sensor may fall out of its ready state. No manufacturer publicly documents a threshold or a bulletin for P22AA, and GM, Ford and VW do not list it in their published tables. CARB asks for continuous monitoring of NOx sensor heater circuits, and smart sensors report the heater circuit state (open, short, no error) over CAN. In practice, check terminal grip, cable routing near hot parts and water ingress. P22A6, P22A8 and P22A9 are the steady faults, P2212 the front sensor.
- What you may notice
- Malfunction indicator lamp that may come and go
- Outlet NOx sensor intermittently not ready
- Likely causes
- LikelyLoose or corroded terminal in the probe connector
- PossibleLead near the exhaust cracked by heat or vibration
- RareIntermittent internal contact fault in the probe
- 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: €50 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.