Fault in the Engine Coolant Temperature Sensor Circuit
Indicates a malfunction in the engine coolant temperature sensor circuit.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The engine coolant temperature sensor measures how hot the coolant is, and if it’s malfunctioning, the computer can’t accurately see if the engine is overheating or running cool.
What the computer is actually seeing
The computer checks for a voltage from the engine coolant temperature sensor in the range of approximately 0.5 to 4.5 volts. If it detects a voltage outside this range, it knows there's a problem with the sensor or wiring.
What a healthy reading looks like
Normal operation should show a voltage of about 2.5 volts at a coolant temperature of approximately 175°F (79°C).
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check the engine coolant level; ensure it’s topped off and not low. If low, refill and see if code returns after a drive cycle.
- 22. Inspect wiring and connectors to the coolant temperature sensor for damage, corrosion, or loose connections. Repair as necessary.
- 33. Using a multimeter, check the voltage at the coolant temperature sensor with the engine running. Expect around 2.5 volts at normal operating temperature. If out of range, proceed to step 4.
- 44. Replace the engine coolant temperature sensor if the voltage is incorrect and wiring looks good. Clear codes and retest.
- 55. If the issue persists, consider having the ECM checked for faults.
Common causes
- Faulty engine coolant temperature sensor
- Wiring issues (shorts, opens, corroded connectors)
- Coolant leaks affecting sensor function
- ECM (Engine Control Module) issues
Typical repair cost
$$
Related codes
Frequently asked questions
Can I still drive the vehicle with this code?
Yes, but monitor the temperature gauge closely, as an inaccurate reading could lead to overheating.
Will the code come back after clearing it?
If the underlying issue isn't fixed, yes, the code will likely return.
Why does this code pair with other sensor codes?
Multiple sensors can fail or be affected by the same wiring issues, leading to multiple fault codes.
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