Cooling System Temperature Sensor
There’s a problem with the 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 measures how hot the engine coolant is. It sends this info to the engine control unit (ECU), which uses it to adjust the engine's performance. When this sensor fails, the ECU might not know if the engine is overheating or running cold.
What the computer is actually seeing
The ECU watches for voltage signals from the temperature sensor. Normal operation usually shows a voltage of about 0.5 volts at cold and up to 4.5 volts at hot. If the signal goes outside of these expected ranges, the ECU triggers this fault code.
What a healthy reading looks like
Expected voltage from the sensor is between 0.5V (cold) to 4.5V (hot). The coolant temperature should be between 190°F to 220°F when at normal operating temperature.
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 wiring and connector of the cooling system temperature sensor for damage or corrosion. If damaged, repair or replace as necessary.
- 22. Ensure coolant level is adequate and that there are no air pockets in the system. Top off coolant if low and bleed air if needed.
- 33. Using a scan tool, check the live data for the coolant temperature. If the readings are stuck or incorrect compared to actual temperature, the sensor is likely faulty.
- 44. Test the resistance of the cooling system temperature sensor. Expect around 0.5k ohm to 5k ohm based on temperature. If reading is outside this range, replace the sensor.
Common causes
- Faulty cooling system temperature sensor
- Wiring issue or connector problem
- Coolant level low or air trapped in the system
- Failed thermostat causing incorrect engine temp readings
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best to not drive it until diagnosed; overheating can cause serious engine damage.
Will this code reset itself?
The code can reset if the issue is fixed, but it won’t go away until the root problem is resolved.
Why is this paired with other codes?
Multiple codes often indicate concurrent issues in the cooling system or sensors working together.
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