P0118 Code: Engine Coolant Temperature (ECT)

p0118 code displaying on an OBD-2 diagnostic tool

P0118 means Engine Coolant Temperature (ECT) Sensor Circuit High Open.

What You'll Read About

What does the P0118 code mean?

The P0118 code means that the Engine Coolant Temperature (ECT) sensor is not reading the correct temperature. A faulty ECT sensor or a bad wiring connection can cause this.

Symptoms of P0118 code

The ECT sensor is a temperature-sensing device that tells the computer how hot or cold the engine coolant is. The computer uses this information to determine how much fuel to inject into each cylinder. If an ECT sensor is not working correctly, it can cause an error code P0118 and prevent your vehicle from starting.

Causes and fixes of P0118 code

If you have a P0118 code, the first thing to check is the wiring. This can be done by using a voltmeter to measure voltages at various points in the circuit. If voltage readings are regular, remove the sensor from its mounting bracket and test its resistance with an ohmmeter or multimeter.

If everything checks out OK so far, something may be wrong with your computer (ECU). Unplugging and reconnecting ECU connectors often fixes this problem as well; if that doesn’t work for you, take it to your local auto repair shop for further diagnosis and repair.

Diagnosing the P0118 code

Check the sensor: The ECT sensor may be dirty or faulty, so checking the sensor response with a multimeter is important. If your car has an automatic transmission, you’ll need to place the gear selector in park or neutral before starting this test (or else you could damage your transmission).

Check the wiring and circuit: Suppose everything checks out okay with your ECT sensor. In that case, it’s time to troubleshoot further by testing for voltage drop on its wiring harnesses and wiring circuits using an accurate voltmeter (if possible). Make sure that all connectors are secure and clean before proceeding further down this path of diagnosis because loose connections can also cause false signals!

Check whether there is any problem with the engine coolant temperature sensor signal output value (as described above), which means looking at both sides of each component involved in sending information back towards ECU through OBD-II connector pins 15(+)and 16(-)