What it means
Intermittent signal from CHT sensor A. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
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 A reports cylinder-head heat to the engine control module, which uses the reading to manage engine operation and temperature protection. This code sets when sensor A’s signal becomes unstable or changes erratically instead of remaining a dependable temperature reading.
Common causes
Most likely first.
- Connector loose or corroded
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
Symptoms
- Check engine light on
- Temperature gauge or warning may behave abnormally
- Engine running or temperature indication may vary intermittently
How to diagnose it
- Check freeze-frame data and live CHT sensor A temperature to see when the signal drops out or jumps.
- With the engine cool, inspect sensor A’s connector for looseness, corrosion, moisture, damaged seals, or pushed-back pins.
- Trace sensor A’s harness for chafing or contact with a vibrating or hot component, and secure any poorly routed section.
- Monitor the live reading while gently moving the connector and harness to reproduce an intermittent fault; note where the value changes.
- If the signal still fluctuates, test sensor A’s wiring continuity and shorts using the vehicle wiring diagram and manufacturer’s specification.
Common fixes
- Reconnect and secure the CHT sensor A connector; clean or repair corroded terminals as appropriate.
- Repair chafed or damaged wiring in the sensor A circuit and secure the harness away from vibration and heat.
- Replace a damaged connector or terminals that cannot maintain contact.
- Replace CHT sensor A if its signal remains erratic with sound wiring and connections.
Can I keep driving?
If the temperature gauge or warning behaves abnormally, avoid hard driving and stop safely if an overheating warning appears; the intermittent reading may prevent reliable temperature monitoring. Have the circuit diagnosed promptly, since overheating could go unnoticed.
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.