Engine Cooling System Temperature Sensor 2 - Voltage Above Normal
The secondary engine coolant temperature sensor is reading higher voltage than expected.
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What it means (plain English)
There's a second sensor in the engine cooling system that detects temperature, and it's showing a higher voltage than it should, meaning it thinks the engine is hotter than it is.
What the computer is actually seeing
The engine control module (ECM) sees the engine coolant temperature sensor 2 output above a set threshold, typically around 4.5 volts for a faulty signal when the expected range is between 0.5 to 4 volts depending on temperature.
What a healthy reading looks like
For normal operation, the voltage output from the secondary coolant temperature sensor should be between 0.5 volts (at around -40°C) and 4.5 volts (at around 140°C).
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 wiring and connectors for the secondary engine cooling temperature sensor for damage, corrosion, or loose connections. Are they in good condition?
- 22. Check the resistance and voltage of the engine coolant temperature sensor during the engine run at normal temperature. Is the output voltage within expected values? (0.5V - 4.5V)
- 33. Verify if the engine coolant is at the correct level. Is it low?
- 44. If wiring and output values are fine, swap the sensor with a known good one. Does the fault clear?
- 55. If the fault persists even after replacing the sensor, check ECM for updates and faults. Any new codes?
- 66. If a new signal pattern isn't established, suspect an issue with the ECM.
Common causes
- Wiring issue or short to voltage
- Failed coolant temperature sensor 2
- Open circuit in sensor wiring
- ECM software corruption
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It’s advisable to fix it soon since an inaccurate temperature reading can lead to overheating and damage over time.
Will this code come back after I clear it?
If the underlying issue isn't resolved, it likely will return.
Why does this code sometimes pair with others?
Multiple sensor failures can occur simultaneously due to shared wiring or common failures in the engine system.
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