P0116 OBD-II Trouble Code: ECT Sensor Circuit Range Performance Problem

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P0116 code definition

Engine Coolant Temperature (ECT) sensor circuit range performance problem

What the P0116 code means

P0116 is the OBD-II generic code that indicates the engine control module (ECM) ECT monitor has read that the ECT sensor range or the sensor performance is not as the ECM expected when starting from a cold start and warm shut down, to the next cold start.

What causes the P0116 code?

When a cold engine is started and warmed up the ECT sensor value does not change.

The warmed up engine ECT sensor value does not change when the engine is stopped and the next cold engine start performed.

What are the symptoms of the P0116 code?

  • The ECM turns on the Check Engine Light and goes into failsafe mode substituting input to 176 degrees Fahrenheit.

  • Engine may have a hard start when engine is cold and start normal when warm

  • Engine may run rough and hesitate until the engine warms up

  • 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 P0116 code?

  • Visually inspects for any electrical connector, wiring, or sensor issues

  • Scans and documents the codes received and views the freeze frame data to see when the code was set

  • Retests the engine to verify any faults present or tries to duplicate the fault with a wiggle test

  • Simultaneously sets codes P0115, P0117, P0118, or P0125 with DTC P0116. The ECT sensor may have an open or short circuit. Diagnoses these codes first.

  • Removes and tests the thermostat to open at the specified temperature

Common mistakes when diagnosing the P0116 code

  • Not performing a visual inspection first

  • Not following the tests for codes P0115, P0117, P0118, or P0125 first if codes were received with P0116

  • Not replacing the thermostat with correct temperature rating

  • Not trying to connect it to view the ECM data and seeing if the temperature output from the sensor is as expected before installation.

How serious is the P0116 code?

  • The P0116 code will cause the engine ECM to go into a failsafe mode.

  • The failsafe mode may cause the engine to run erratic with hesitation or rough running, until the engine has been warmed up.

What repairs can fix the P0116 code?

  • Testing and replacing the thermostat
  • Testing and repairing any other ECT codes, such as P0115, P0117, P0118, P0119 or P0125

Additional comments for consideration regarding the P0116 code

  • The P0116 code is often associated with P0115, P0117, P0118, P0119 or P0125 codes.
  • Most failures for code P0116 is a thermostat not working properly.

Need help with a P0116 code?

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

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