P00D4HO2S Heater Control Circuit Range/Performance Bank 2 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
- This code concerns the heated oxygen sensor behind the catalytic converter (sensor 2) on bank 2. Unlike the heater circuit codes, which report an open or short circuit, this code means the heater is driven but does not bring the oxygen sensor to the expected temperature. One documented method, used where no current-measuring shunt is fitted, measures the internal impedance of the sensor element: a hot element has a low impedance. If the impedance stays above a limit that depends on the calculated element temperature and the voltage at the sensor connector, the heating is judged insufficient. The test runs once per trip. Typical causes are an aged heating element or added resistance from corrosion in the heater circuit. Bank 2 exists only on V and boxer engines.
- What you may notice
- Check engine light on
- Usually no noticeable drivability problem
- Oxygen sensor heater readiness stays incomplete
- Likely causes
- LikelyHeating element aged, resistance increased
- LikelyCorrosion or contact resistance at connector or harness of the heater circuit
- PossibleToo low supply voltage at the sensor connector, e.g. poor ground
- PossibleDiagnostic software (manufacturer updates exist for some vehicles)
- RareReplacement sensor with a different heater
- 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 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.