Engine Coolant Temperature Sensor 1 Voltage High
The voltage from the engine coolant temperature sensor is higher than expected.
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 measures how hot the engine is running; if it shows a high voltage, it might read temperatures that are not correct, typically over 4.5 volts.
What the computer is actually seeing
The engine control module (ECM) sees a voltage reading from the coolant temperature sensor that exceeds 4.5 volts, indicating a potential fault in the sensor or its wiring.
What a healthy reading looks like
The coolant temperature sensor should provide a voltage between 0.5 to 4.5 volts depending on coolant temperature; at 190°F, it should be around 2.5 volts.
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.
- 1Check the wiring and connector for the coolant temperature sensor for damage, corrosion, or looseness.
- 2Measure the voltage at the coolant temperature sensor connector with the key ON (engine off); it should be between 0.5 to 4.5 volts based on temperature.
- 3If the voltage is above 4.5 volts, disconnect the sensor and check the voltage at the harness connector again; if it stays high, there's likely a wiring issue.
- 4If the voltage drops as expected when the sensor is disconnected, replace the coolant temperature sensor.
Common causes
- Faulty coolant temperature sensor
- Wiring issues or short to positive within the sensor circuit
- Poor connector fit or corrosion
- Failed ECM (rare)
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's not recommended to drive long distances; the engine may run inefficiently or overheat.
Will this code clear itself?
If the issue causing the high voltage is resolved, the code should clear after a few drive cycles.
Why do I see this code with low coolant?
Low coolant can cause incorrect readings from the sensor, contributing to high voltage faults.
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 →