Engine Cooling System Temperature Sensor 1
Indicates a fault with the engine cooling system 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 cooling system temperature sensor monitors how hot the engine coolant is. It sends this info to the engine control module (ECM) to manage engine performance; if it fails, the ECM might not know if the engine is overheating or running cold.
What the computer is actually seeing
The PCM (Powertrain Control Module) looks for voltage signals from the coolant temperature sensor that should range from 0.5V (cold engine) to 4.0V (hot engine). If the voltage stays constant or is out of this range, the fault code triggers.
What a healthy reading looks like
0.5V at 32°F, rising to approximately 4.0V at 248°F, with a linear relationship.
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 coolant level and top off if low.
- 2Inspect both ends of the wiring harness for damage, wear, or corrosion.
- 3Measure voltage at the coolant temperature sensor with the engine running; should be between 0.5V to 4.0V based on temperature.
- 4If the voltage is inconsistent, replace the sensor; if it remains constant, check wiring integrity further.
Common causes
- Failed coolant temperature sensor
- Wiring issues (shorts or opens)
- Corroded connectors
- Coolant leaks affecting sensor function
Typical repair cost
$$$
Related codes
Frequently asked questions
Why does this code sometimes pair with other codes?
Sensor failures can affect multiple systems, leading to related error codes appearing together.
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