P CODES (POWERTRAIN) P0100 - P0199 P0117


    The P0117 code indicates that the Engine Control Module (ECM) has detected a low input signal from the Engine Coolant Temperature (ECT) sensor. This means that the temperature of the engine coolant is not being measured correctly, which can lead to poor engine performance, decreased fuel efficiency, and potential engine damage. In this guide, we will discuss what the P0117 code means and provide step-by-step instructions on how to troubleshoot and fix the problem.

    Step 1: Understand the Engine Coolant Temperature Sensor

    The Engine Coolant Temperature (ECT) sensor is located on the engine and is responsible for measuring the temperature of the engine coolant. This information is sent to the Engine Control Module (ECM), which uses it to adjust engine performance and fuel efficiency. The ECT sensor is a thermistor, which means its resistance changes as the temperature of the coolant changes. When the engine is cold, the resistance is high, and as the engine warms up, the resistance decreases.

    Step 2: Check the ECT Sensor Wiring

    The first step in troubleshooting the P0117 code is to check the wiring and connectors of the ECT sensor. Make sure that the wiring is not damaged, corroded, or disconnected. Inspect the connectors for any signs of damage or corrosion. If the wiring and connectors appear to be in good condition, move on to the next step.

    Step 3: Test the ECT Sensor

    The next step is to test the ECT sensor itself. To do this, you will need a multimeter. Disconnect the wiring connector from the sensor and set your multimeter to measure resistance. Place the multimeter leads on the two terminals of the sensor and record the resistance. Compare the resistance reading to the specifications provided in the vehicle's service manual. If the resistance reading is outside of the specified range, replace the ECT sensor.

    Step 4: Check the Coolant Level

    If the ECT sensor is functioning correctly, the next step is to check the coolant level in the engine. A low coolant level can cause the engine to run hot, which can affect the performance of the ECT sensor. Make sure the coolant level is at the correct level and add more coolant if necessary.

    Step 5: Check the Thermostat

    If the coolant level is correct, the next step is to check the thermostat. The thermostat regulates the flow of coolant through the engine and can affect the performance of the ECT sensor. Make sure the thermostat is functioning correctly and replace it if necessary.

    Step 6: Check for Engine Cooling System Issues

    If the thermostat is functioning correctly, the next step is to check for any issues with the engine cooling system. Make sure that the radiator is not clogged or damaged, the water pump is functioning correctly, and the hoses are not damaged or leaking. Any issues with the cooling system can affect the performance of the ECT sensor.

    Step 7: Check the Engine Control Module

    If all of the above steps have been completed, and the problem still persists, it is time to check the Engine Control Module (ECM). A malfunctioning ECM can send incorrect signals to the ECT sensor, which can result in the P0117 code. Have the ECM scanned and diagnosed by a qualified mechanic. If necessary, replace the ECM.


    Troubleshooting the P0117 code requires a step-by-step approach, starting with checking the ECT sensor wiring and connectors, and testing the sensor itself. If the ECT sensor is functioning correctly, check the coolant level, thermostat, and engine cooling system for issues. If the problem still persists, check the Engine Control Module. By following these steps, you can fix the problem

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