Skip the auto shop - Our mechanics make house calls

P0117 OBD-II Trouble Code: Engine Coolant Temperature (ECT) Sensor Circuit Low Output Problem

Check Engine Light

P0117 code definition

Engine Coolant Temperature (ECT) sensor circuit low output problem

What the P0117 code means

P0117 is the OBD-II generic code that indicates the engine control module (ECM) has seen the ECT sensor output go less than 0.14 Volts or more than 140°C (284°F).

What causes the P0117 code?

  • ECT sensor input to the ECM went to more than 0.14 Volts or 140°C (284°F) indicating a short circuit in sensor or wiring.

  • The ECT sensor or wiring is shorted.

What are the symptoms of the P0117 code?

  • ECM turns on the Check Engine Light and goes into failsafe mode substituting input to 176° F.
  • The engine may have a hard start when engine is cold.
  • The engine may run rough and hesitate until the engine warms up.
  • The engine should run close to normal once the engine warms up.

Note: The symptoms are determined by the manufacturer failsafe ECM strategy for the vehicle during a failure and may vary between manufacturers and vehicles.

How does a mechanic diagnose the P0117 code?

  • A visual inspection to check for any electrical connector, wiring or sensor issues.

  • The technician will scan and document the codes received and view the freeze frame data to see when the code was set.

  • The codes should then be reset to clear the OBD-II fault codes and retest the vehicle to see if the code comes back.

  • Disconnect ECT sensor, observe live data to see if readings go from over 284°F to -40°F.

  • If readings go to -40° F then replace the ECT sensor if not then look for shorted harness, connector or ECM.

Common mistakes when diagnosing the P0117 code?

Not following these simple steps:

  • Always do a visual inspection first.

  • The manufacturer pinpoint test procedure follow step-by-step not skipping any steps.

  • Do not replace an ECT sensor unless tests indicate a problem.

  • Before installation of the new ECT sensor, try connecting it and viewing the ECM data to see if the temperature output from the sensor is as expected.

How serious is the P0117 code?

  • The P0117 code will put the engine ECM to go into a failsafe mode.

  • The failsafe mode may cause engine to run rough and hesitate until the engine warms up to operating temperature.

  • Electrical cooling fans may run continuously.

What repairs can fix the P0117 code?

  • Resetting the fault codes and perform a road test
  • Repairing or replacing the ECT connector
  • Repairing or replacing the wiring as necessary
  • Replacing the ECT with a new sensor

Additional comments for consideration regarding the P0117 code

  • The ECT sensor shorted is the most common failure.

  • Some failures for code P0117 other than the sensor include a harness shorting or a connector corrosion issue.

Need help with a P0117 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.


Post a question and get free advice from our certified mechanics.


More related articles

P0222 OBD-II Trouble Code: Throttle/Pedal Position Switch/Sensor B Circuit Low Input
P0222 code definition Throttle/Pedal Position Switch/Sensor B Circuit Low Input What the P0222 code means The manufacturer specifies a range of acceptable voltage to be produced from the throttle position...
Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...
P2159 OBD-II Trouble Code: Vehicle Speed Sensor B Range/Performance
Diagnostic Trouble Code (DTC): P2159 P2159 code definition Vehicle Speed Sensor B Range/Performance Related Trouble Codes: P2158: Vehicle Speed Sensor B P2160: Vehicle Speed Sensor B Circuit Low P2161:...

Related questions

Q: Limp mode

If you do not use the recommended fluid for Chrysler or any transmissions in general, it can cause the transmission to have shifting and slipping concerns. Even damage can be caused from incorrect fluids being used. This is why I...

Q: Trouble running when the engine warms up, dash lights on - 2007 Subaru B9 Tribeca

The P0137/P0157 codes indicate the "rear" (behind the catalytic converters) oxygen sensors are not functioning properly. In turn, they are signaling (incorrectly) for more fuel, which is causing the P0172/P0175 over-rich codes. This is clogging your converters, as well as...

Q: p0117 code and engine heating to 75% of temp gauge (but no further)

You will have to scan the computer when the engine is cold and look at the data to compare the ECT and the IAT. This is the inlet air temperature sensor and the engine coolant temperature sensor. Both sensors will...