Cooling System Temperature Sensor 1 Fault
This code indicates a problem with the cooling system temperature sensor 1.
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 1 is giving readings that don’t match what the engine expects, which can lead to incorrect engine temperature monitoring and coolant issues.
What the computer is actually seeing
The engine control unit (ECU) receives temperature readings from the sensor. When the temperature reading is outside the expected range (such as below 150°F or above 250°F when the engine is operating), the code is triggered.
What a healthy reading looks like
The sensor should output a voltage between 0.5V (cold) and 4.5V (hot); normal operating temps should be around 180°F to 210°F, translating to expected sensor voltage of approximately 1.0V to 2.5V.
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; it should be between the minimum and maximum marks. Fill if low. -> Go to step 2.
- 22. Inspect the wiring and connectors to the cooling system temperature sensor 1 for damage or corrosion. Repair any issues found. -> Go to step 3.
- 33. Measure the voltage output from the sensor with the engine at operating temperature. It should be between 1.0V and 2.5V. -> If outside this range, replace the sensor. -> If within range, go to step 4.
- 44. Check the ECU for any stored codes or pending codes. Clear the codes and retest the system. -> If the code returns, further diagnostics on ECU connections may be necessary.
Common causes
- Faulty cooling system temperature sensor
- Wiring issues (shorts, opens, corrosion)
- Bad ECU connection
- Coolant leaks affecting sensor performance
- Incorrect coolant level impacting temperature readings
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's moderate severity, so it’s advisable to fix soon to avoid overheating issues.
Will this code come back after clearing it?
If the underlying issue isn't fixed, yes, it is likely to return.
Why does it pair with other codes?
Multiple faults can arise from the same sensor or wiring issues.
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