P00B6Radiator Coolant Temperature/Engine Coolant Temperature Correlation
- 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
- The radiator coolant temperature sensor is an NTC thermistor that measures coolant temperature on the radiator side, typically at the radiator outlet; the exact position depends on the manufacturer. Together with the engine coolant temperature sensor it gives a second measuring point, which the control module uses to diagnose the thermostat and coolant flow, for example on engines with an electrically heated map-controlled thermostat. After a long standstill (eight hours in a documented case) engine and radiator should be at the same temperature. P00B6 is set at the next start when the engine and radiator coolant temperature sensors differ by more than a threshold that may depend on intake air temperature. A detected engine block heater cancels the test. From this alone the control module cannot tell which sensor is wrong.
- What you may notice
- Check engine light on
- Usually no noticeable symptoms
- Likely causes
- LikelyRadiator coolant temperature sensor drifting
- LikelyEngine coolant temperature sensor drifting
- PossibleContact resistance at a connector
- PossibleRetrofitted engine preheater or auxiliary heater not detected by the system
- 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 – €200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.