P00B6
Radiator Coolant Temperature/Engine Coolant Temperature Correlation
Engine cooling
Generic OBD-II
High
What it means
P00B6 sets when the radiator coolant temperature sensor and the engine coolant temperature sensor disagree by more than the ECM allows. Usually one sensor is reading wrong, but it can also mean a genuine temperature split from a stuck thermostat or low coolant. The engine keeps running, but it's worth checking so a real cooling problem isn't missed.
High
Can I keep driving? Driveable in the short term, but watch the temperature gauge — a real coolant-temperature split can point to a cooling problem, so don't ignore it.
Common symptoms
What you'll notice
- Check-engine light on
- Cooling fans running more or less than expected
- Temperature gauge reading inaccurately or erratically
- Possible rough or hesitant running when cold
Common causes
Most likely first
- Faulty radiator (outlet) coolant temperature sensorLikely
- Faulty engine coolant temperature sensorCommon
- Stuck-open thermostat creating a genuine temperature differenceCommon
- Low coolant levelLess often
- Wiring or connector fault at one of the sensorsLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and check coolant level first.
- With the engine cold (overnight soak), compare both coolant sensor readings on a scan tool — they should read close to ambient and to each other.
- Inspect the connectors and wiring at both sensors for corrosion or damage.
- Measure the suspect sensor's resistance against a temperature chart and replace the one reading off.
- If both sensors check out, verify thermostat operation. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P00B6?+
Short trips are usually fine, but because it can reflect a real cooling issue, keep an eye on the temperature gauge and stop if the engine overheats.
Can I just clear P00B6?+
It returns once the two sensors disagree again. Fix the off-reading sensor, low coolant, or thermostat first.
Related codes
Often seen with P00B6
Read & clear P00B6 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX