P0117: Engine Coolant Temperature Sensor 1 Circuit Low
What to do
If the fans are running constantly and the gauge reads normal, the sensor is the likely problem rather than genuine overheating. Still worth checking coolant level to be certain.
What this code means
The coolant temperature signal is below its valid range, normally a short to ground, which the module reads as an implausibly high temperature. Depending on the strategy this may trigger the cooling fans permanently and pull timing to protect the engine — so the symptoms can look alarming while the engine itself is perfectly healthy.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Faulty engine coolant temperature sensor · easy
Less common
- Corroded or loose connector · easy
- Chafed harness against engine or bracket · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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