OBD codes / P0117
P0117
ModerateEngine Coolant Temperature (ECT) Sensor Circuit Low
P0117 is usually drivable short-term, but verify the engine isn't actually overheating — the gauge may read high because of the false signal. If the engine genuinely runs hot, treat that as urgent. Otherwise, get the sensor or wiring fixed soon; a false hot reading affects fueling and fan operation.
What this code means
The engine coolant temperature (ECT) sensor reports engine temperature to the computer. P0117 means that sensor's signal is reading low — which the computer interprets as extremely HOT (or a wire shorted to ground). It's the mirror of P0118. The usual cause is a failed sensor or a wire shorted to ground, occasionally a corroded connector. A false "hot" reading can lean out the fuel mixture, run the cooling fans constantly, or even push the car into a protective mode, so it's worth fixing rather than ignoring.
Symptoms you might notice
- Check-engine light
- Cooling fans running constantly
- Temperature gauge reading high when the engine isn't actually hot
- Possible rough running or reduced power
- Hard starting in some cases
What it costs to fix
Typical range: $40–$250 · about ~0.3–1.5 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| ECT sensor | $15–$80 | ~0.3–1 hrs |
| Wiring / connector repair | $10–$120 | ~0.5–1.5 hrs |
The sensor is inexpensive and usually easy to reach, so this is typically a low-cost repair. A wiring short can take a little longer to find but the parts are cheap.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0117 for my exact vehicle →
Frequently asked
Can I drive with P0117?
Short-term usually yes, but first make sure the engine isn't truly overheating — the sensor may be falsely reading hot. If it's just the sensor, the car runs fine; fix it soon so fueling and fans behave normally.
What does "circuit low" mean for P0117?
The sensor's voltage is at the low end, which the computer reads as extremely hot or as a wire shorted to ground. That points to a failed sensor or a short rather than a real temperature.
Is P0117 the same as P0118?
Same sensor, opposite reading: P0117 reads too low (interpreted as hot/shorted), P0118 reads too high (interpreted as cold/open). Both are usually a sensor or wiring fix and are diagnosed the same way.
How much does it cost to fix P0117?
Usually inexpensive — the ECT sensor is cheap and easy to reach on most engines; a wiring repair is modest. Check the wiring before replacing the sensor.
Seeing P0117 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0117 for my vehicleGeneric OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.