Coolant Temperature Sensor Out of Range
The coolant temperature sensor is reporting values outside the normal operating range.
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What it means (plain English)
The coolant temperature sensor measures how hot the engine coolant is. If it gets too high (over 240°F) or too low (under 160°F), the engine computer gets a signal that there's a problem, which can affect engine performance.
What the computer is actually seeing
The engine control module (ECM) monitors readings from the coolant temperature sensor for expected values. It expects to see a voltage between 0.5V (about 160°F) and 4.5V (about 240°F). If it sees a voltage lower than 0.5V or higher than 4.5V, it triggers this fault code.
What a healthy reading looks like
Coolant temperature should be between 160°F (0.5V) and 240°F (4.5V).
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 coolant level; if it's low, refill and retest.
- 22. Inspect the wiring and connector to the coolant temperature sensor for any signs of damage or corrosion; repair if found and retest.
- 33. Using a scan tool, monitor the actual coolant temperature reading in live data during a warm-up cycle; it should smoothly increase without spikes or drops.
- 44. If the readings are erratic or outside the expected values, replace the coolant temperature sensor and retest.
- 55. If the condition persists after sensor replacement, consider checking the ECM for errors or reprogramming.
Common causes
- Faulty coolant temperature sensor
- Wiring issues or damaged harness
- ECM software glitch or failure
- Coolant level low
- Corrosion at sensor connector
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's safe to drive short distances, but plan to fix it soon as it can affect engine performance and emissions.
Will this code come back after I fix it?
If you address the underlying issue (like a faulty sensor or bad wiring), it shouldn't come back.
Why does this code often pair with SPN 2656?
SPN 2656 indicates a similar issue with the coolant temperature sensor circuit, so they often appear together when there's a wiring problem or sensor failure.
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