Engine Coolant Temperature Sensor Circuit High
The engine coolant temperature sensor is reading a high voltage output.
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 coolant temperature sensor sends a signal to the engine control module (ECM) about how hot the engine's coolant is. If the voltage is too high, it may indicate a faulty sensor or wiring issue, often reading over 4.5 volts when the normal range should be lower.
What the computer is actually seeing
The ECM expects to see a voltage between 0.5V and 4.5V from the coolant temperature sensor. A reading above 4.5V is interpreted as a fault condition, indicating that the sensor is likely malfunctioning.
What a healthy reading looks like
Normal operation should see the coolant temperature sensor output between 0.5V (cold engine) to 4.5V (hot engine). A reading consistently above 4.5V indicates a problem.
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. Inspect the wiring and connectors at the coolant temperature sensor for signs of damage or corrosion. If found, repair or replace as needed. Decision: If wiring/connectors are fine, proceed to step 2. If damaged, fix and retest.
- 22. Disconnect the coolant temperature sensor and check the voltage output at the connector while the ignition is on. Expected voltage should be below 4.5V. Decision: If the voltage is high, replace the sensor. If the voltage is normal, check for shorts to power in the sensor circuit.
- 33. If the sensor is replaced, clear the fault codes and monitor for return of the SPN 1145 code during engine operation.
Common causes
- Faulty coolant temperature sensor
- Damaged wiring or connector
- Corrosion in sensor connector
- Short circuit to power supply
- Open circuit in sensor circuit
Typical repair cost
$$-$$$
Related codes
Frequently asked questions
Can I drive my vehicle with this code?
It's drivable but not recommended to ignore. The vehicle may run rich or lean, which can lead to engine damage over time.
Will this code clear itself after a repair?
Yes, after fixing the issue, clearing the code may be needed and should not return if repaired correctly.
Why does this code show up with other codes?
It's common for multiple sensor issues to arise together, especially if there’s a wiring problem; addressing the root cause can resolve multiple codes.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →