Engine Coolant Temperature Sensor Circuit High
Table of contents
P0118 MERCURY Possible Causes
- Low engine coolant level
- Faulty engine coolant thermostat
- Faulty Engine Coolant Temperature (ECT) Sensor or Cylinder Head Temperature (CHT) Sensor
- Engine Coolant Temperature Sensor or Cylinder Head Temperature Sensor harness is open or shorted
- Engine Coolant Temperature Sensor or Cylinder Head Temperature Sensor circuit poor electrical connection
How do I fix code P0118 MERCURY?
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.
Tech Notes
- Start by checking for coolant leaks, and if there are no leaks, the thermostat might be stuck closed and needs replacement. If the problem persists, change the Engine Coolant Temperature (ECT) sensor.
Cost of diagnosing the P0118 MERCURY code
The cost of diagnosing the P0118 MERCURY code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
P0118 MERCURY Description
The Engine Coolant Temperature (ECT) sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from the Powertrain Control Module (PCM). The modified signal returns to the PCM as the engine coolant temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases. The Diagnostic Trouble Code (DTC) indicates the sensor signal is greater than the self-test maximum. The ECT sensor maximum is 4.6 volts or -50°C (-58°F).