Engine Coolant Temperature Sensor 1
Indicates a problem with the engine coolant temperature sensor.
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 the temperature of the coolant, helping the computer control engine performance and emissions. If it reads incorrectly, the engine may run poorly or not at all.
What the computer is actually seeing
The engine control module (ECM) reads voltage signals from the coolant temperature sensor. Typically, the sensor should output a voltage between 0.5V (at -40°C) and 4.5V (at 150°C). A reading outside this range can trigger the fault code.
What a healthy reading looks like
0.5V to 4.5V corresponding to temperatures from -40°C to 150°C (or -40°F to 302°F).
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 coolant level in the reservoir; refill if low. Decision: If low, fill and retest. If not low, proceed.
- 22. Inspect wiring and connector to the coolant temperature sensor for damage or corrosion. Decision: Repair any issues found; retest.
- 33. Measure voltage at the coolant temperature sensor harness with the engine running. Expected: 0.5V to 4.5V. Decision: If outside range, replace the sensor. If within range, proceed to step 4.
- 44. Check for any additional fault codes related to the ECM or coolant system. Decision: Address any additional codes found.
Common causes
- Faulty coolant temperature sensor
- Wiring issues or poor connections
- Coolant leaks causing low levels
- Faulty engine control module (ECM)
Typical repair cost
$$
Related codes
Frequently asked questions
Can I drive with this code active?
Yes, but drive with caution. It won't cause immediate danger, but your engine performance may be affected.
Will this code come back after I clear it?
If the underlying issue isn't fixed (e.g., sensor or wiring problem), the code will likely return.
Why does this code sometimes pair with other codes?
Faulty sensors or wiring in one area can lead to multiple faults triggering due to shared circuits or issues.
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