What it means
The ECM detects a range/performance fault on the cylinder head temperature sensor b. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Cylinder head temperature sensor B measures temperature at its position in the cylinder head and provides that reading to the ECM. This range/performance code sets when the signal is present but does not match the temperature range or response the ECM expects.
Common causes
Most likely first.
- Sensor characteristic drifted
- Sensor mounting displaced
- Sensor element aged beyond calibration window
Symptoms
- Check-engine light
- Engine temperature reading may be inaccurate
- Hard starting
How to diagnose it
- Use freeze-frame data and compare sensor B's reading with other temperature readings after a cold soak, when they should be broadly consistent.
- Inspect sensor B's mounting and connector for displacement, poor contact, contamination, or heat-related harness damage.
- Monitor sensor B through warm-up and compare its rate of change and temperature values with the manufacturer's specifications.
- Check sensor B's reference, ground, and signal wiring for resistance changes, shorts, or intermittent contact.
- If mounting and wiring are correct but the signal remains outside the expected response, test or replace sensor B and recheck its readings.
Common fixes
- Correct sensor B's mounting so it measures cylinder head temperature as intended.
- Clean and secure the connector and repair any damaged wiring.
- Replace cylinder head temperature sensor B if its response has drifted outside the manufacturer's specification.
- Clear the code and verify a plausible sensor B temperature rise during warm-up.
Can I keep driving?
Drive only while temperature indications remain normal, and stop if an overheat warning appears because a misleading sensor reading can delay recognition of overheating. Avoid extended trips until sensor B's accuracy is restored.
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.