Engine Coolant Temperature
This code indicates a problem with the engine coolant 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 engine coolant temperature sensor measures the temperature of the coolant. If it's not reading correctly, the engine control unit (ECU) can’t adjust fuel injection and ignition timing properly, which could lead to overheating or inefficient fuel consumption.
What the computer is actually seeing
The ECU expects a voltage between 0.5V (at -40°C) and 4.5V (at 150°C). If the temperature goes beyond an expected range or the sensor fails, the ECU triggers this code.
What a healthy reading looks like
Coolant temperature should typically be around 85-105°C during normal operation with corresponding sensor voltage of approximately 0.5V to 4.5V.
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 and ensure there are no leaks.
- 22. Inspect the wiring and connectors for any damage or corrosion.
- 33. Using a scan tool, monitor the actual coolant temperature while the engine runs. Compare this with the expected temperatures from the engine diagnostics.
- 44. If the sensor reading is erratic or out of range, replace the coolant temperature sensor and retest.
- 55. Clear the code and see if it returns after a drive cycle.
Common causes
- Faulty coolant temperature sensor
- Wiring issues or short circuits
- Connector corrosion or loose connections
- Low coolant levels or air in the system
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best to fix it soon as it can affect engine performance and fuel efficiency.
Will this issue come back after I clear the code?
If the underlying cause isn’t addressed, it will likely return.
Why does this code pair with SPN 29?
SPN 29 also relates to coolant temperature issues, often indicating the sensor is not functioning properly.
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