What it means
The radiator coolant temperature sensor reading is outside the expected range or does not behave as expected.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The radiator coolant temperature sensor reports coolant temperature so the control module can assess radiator temperature and cooling-system behavior. P00B2 sets when that reading is outside the expected range or changes in a way the module considers implausible, which can result from a sensor, its mounting, or actual coolant warm-up behavior.
Common causes
Most likely first.
- Thermostat stuck open
- Sensor element aged beyond calibration window
- Sensor mounting loose - signal damping
Symptoms
- Check engine light on
- Temperature gauge may read incorrectly or fluctuate
- Cooling fan may run unusually or not operate as expected
How to diagnose it
- Save freeze-frame data and compare radiator and engine coolant temperature readings with ambient temperature after the engine has cooled.
- Watch both coolant temperature readings during warm-up to see whether the radiator reading changes plausibly and whether the engine takes unusually long to warm.
- Inspect the radiator sensor's seating, connector, and wiring for looseness, corrosion, or damage that could distort its reading.
- Check thermostat operation and coolant circulation if the temperature trend suggests the engine is warming too slowly or unevenly.
- Test the radiator coolant temperature sensor against the manufacturer's specification and replace it only if it is out of range.
Common fixes
- Secure the radiator coolant temperature sensor in its proper mounting.
- Repair a loose, corroded, or damaged sensor connector or wiring.
- Replace a thermostat that fails the specified operation check.
- Replace the radiator coolant temperature sensor if its readings fail the manufacturer's test.
Can I keep driving?
A faulty temperature reading can cause unusual fan operation and may hide a developing cooling problem. Watch the gauge and stop driving if the engine overheats.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.