Error P0117 – how to fix?

Code Definition P0117

An engine coolant temperature (ECT) sensor output problem is low.

What does the code P0117 mean

P0117 is a generic OBD-II code indicating that the engine control module (ECM) has noticed the ECT sensor output is below 0.14 V or above 140 ° C (284 ° F).

What causes the code P0117?

The ECT sensor input to the ECM has exceeded 0.14 V or 140 ° C (284 ° F), indicating a short circuit in the sensor or wiring.

The ECT sensor or wiring harness is shorted.

What are the symptoms of the P0117 code?

• The ECM turns on the check engine light and enters safety mode by overriding the 176 ° F input.
• The engine may have difficulty starting when the engine is cold.
• Engine may run jerky and hesitate until warm.
• The engine should run almost normally after warm up.

Note: Symptoms are determined by the manufacturer’s ECM safety strategy for the vehicle during a fault and may vary by manufacturer and vehicle.

How does the mechanic diagnose the P0117 code?

• Visual inspection to check for problems with electrical connectors, wiring, or sensors.
• A technician scans and documents the codes received, and reviews the data from the frozen frames to see when the code has been set.
• The codes must be reset to clear the OBD-II fault codes and retest the vehicle to see if the code has returned.
• Disconnect the ECT sensor, watch live data to see if the readings change from over 284 ° F to -40 ° F.
• If the readings are -40 ° F, replace the ECT sensor, otherwise look for a short in the harness, connector or ECM.

The most common errors when diagnosing the P0117 code.

• Don’t follow these simple steps:
• Always perform a visual inspection first.
• Follow the manufacturer’s test procedure step by step without skipping any step.
• Do not replace the ECT sensor unless testing shows a problem.
• Before installing a new ECT sensor, try connecting it and looking at the ECM data to see if the temperature output from the sensor is as expected.

How serious is the P0117 code?

• Code P0117 will cause the engine ECM to enter fail-safe mode.
• Degraded mode can cause the engine to run poorly and hesitate until the engine is warmed up to operating temperature.
• Electric cooling fans can run continuously.

What repairs can fix the code P0117?

1. Reset fault codes and run road test.
2. Repair or replace the ECT connector
3. Repair or replace the wiring as needed
4. Replace the ECT with a new sensor

Additional notes regarding code P0117

1. The ECT sensor short circuit is the most common malfunction.
2. Some errors for the P0117 code other than the sensor include a short in the harness or a corrosion problem in the connector.