The most common causes are: Failed ECT sensor (internally shorted); Short to ground in the sensor signal wire; Corroded or damaged connector; Genuine overheating — always rule this out first; Wiring damage from engine heat.

How much does it cost to fix P0117?

Typical repairs range from $80–$300 for repair shorted wiring up to $150–$1,000 for address genuine cooling system fault. Costs vary by vehicle and region.

P0117powertrain

P0117 – Engine Coolant Temperature Circuit Low Input

What does P0117 mean?

The engine coolant temperature (ECT) sensor circuit is reading low voltage, which the computer interprets as an implausibly high temperature. Because coolant temperature drives fuel enrichment and cooling fan operation, an incorrect reading affects several systems.

What causes P0117?

Listed from most to least common:

1Failed ECT sensor (internally shorted)
2Short to ground in the sensor signal wire
3Corroded or damaged connector
4Genuine overheating — always rule this out first
5Wiring damage from engine heat

Code breakdown

SystemP — Powertrain

TypeGeneric (standardized SAE / OBD-II code — same meaning across most manufacturers)

SubsystemFuel and air metering

Common symptoms

Check engine light on
Cooling fans running continuously
Hard starting when cold
Poor fuel economy
Temperature gauge reading incorrectly high

How to diagnose

1Confirm the engine is not actually overheating — check coolant level and feel for genuine heat before condemning the sensor.
2Compare the live ECT reading against actual engine temperature measured with an infrared thermometer.
3Disconnect the sensor. If the reading swings to the opposite extreme, the wiring is intact and the sensor is likely at fault.
4Inspect the signal wire for chafing or shorting to ground against the engine.
5Measure sensor resistance cold and compare against the manufacturer's temperature/resistance table.

The computer may lean out the mixture believing the engine is hot, and cooling fans may run constantly. Verify the engine is not genuinely overheating before assuming a sensor fault.

Common fixes and estimated costs

Repair	Estimated cost
Repair shorted wiring	$80–$300
Replace ECT sensor	$60–$200
Address genuine cooling system fault	$150–$1,000

Costs are rough US estimates including parts and labor. Actual pricing varies significantly by vehicle, region, and shop rates.

Good to know

Never assume this is only a sensor problem. Rule out real overheating first — an actual cooling system failure that gets misdiagnosed as a bad sensor can lead to a warped head or blown gasket.

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This information is provided for general reference only and may vary by manufacturer, model, and year. It is not a substitute for professional diagnosis or repair.