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P2184 OBD-II Trouble Code: Engine Coolant Temperature Sensor 2 Circuit Low

Check Engine Light

P2184 code definition

P2184 is an OBD-II generic code for the engine control module (ECM) detecting the engine coolant temperature sensor (ECT) #2 is indicating low range and does not correlate with ECT sensor #1.

What causes the P2184 code?

  • The engine control module (ECM) checks the ECT and ambient temperature sensors when the engine is first started cold to see if the sensors correlate with each other and with the ambient air temperature sensor.

  • The ECT sensor is not reading within a specified range and is too low when compared to the other sensors.

  • The ECT sensor is too low and is not correlating to the #1 ECT sensor reading and the ambient temperature sensor.

What are the symptoms of the P2184 code?

  • The Check Engine Light will be illuminated and the code is set in the ECM memory as a fault.

  • The ECM will ignore the ECT #2 sensor and will retest it each time the engine has a cold start to verify the failure is still active or not.

  • The engine should run normally as long as the #1 sensor is not having a problem and correlates to the ambient air temperature sensor.

  • The only symptom will be the Check Engine Light not being on as long as only one sensor is failing.

How does a mechanic diagnose the P2184 code?

  • Scans for codes and documents the code in the ECM and looks at the freeze frame data for failure

  • Scans the engine only after the engine has been sitting for at least 8 hours and the coolant is at ambient temperature

  • Scans the ECM and checks readings from the two ECT sensors and the ambient air temperature sensor to see if the ECT #2 sensor is reading a lower temperature than the other two sensors. All three should be within a few degrees of each other

  • Checks the #2 ECT sensor connector for problems like loose or corroded pins

  • Replaces the #2 ECT sensor if all wiring checks out okay and the Ohm's test shows that it is out of specifications

Common mistakes when diagnosing the P2184 code

  • Clearing ECM memory codes before checking the freeze frame data for the main failure problem, so the failure may be duplicated and repaired

  • Failing to clear the ECM codes after the codes are fixed so the ECM will be able to monitor the system like normal again

  • Failing to identify and repair any connector issues before replacing the ECT sensor

How serious is the P2184 code?

  • Code P2184 is a code indicating the number 2 ECT sensor does not match the #1 sensor, and if this sensor fails, then the engine will have running issues. This will fail the vehicle for emissions testing and cause the engine to run too rich during the failure.

What repairs can fix the P2184 code?

Additional comments for consideration regarding the P2184 code

Code P2184 is for the second ECT sensor. The engine has two sensors to back up each other in case of a failure to keep the engine running smoothly. This is so that one failure does not cause any running issues with the engine except for turning on the Check Engine Light.

Failure to fix the problem will keep the Check Engine Light on, and if another fault happens, you would not be alerted to an issue since the Check Engine Light would already be on. In addition, this failure will cause your vehicle to not pass your emission testing in most states and would need to be repaired before retaking the test.

Need help with a P2184 code?

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