Is It Safe to Drive With a P0118 Code?
Common Symptoms of a P0118 Fault
EML on
Possible lean running
Cooling fan may run constantly
Temperature gauge may read maximum
Possible Causes of P0118
A P0118 code can be triggered by faults across several systems. Identifying the exact root cause requires proper diagnostic equipment and live data — not just reading the code.
ECT Sensor Open Circuit
Wiring has an open circuit causing a high voltage reading.
ECT Sensor Failure
Sensor failed open-circuit internally.
Connector Fault
Poor connection or corrosion in sensor connector.
ECU Input Fault
ECU input circuit for the ECT sensor.
Why we don't list the exact part: A P0118 code tells you what's happening but not why. Replacing parts based on the code alone is the most common way drivers waste money. A proper diagnosis identifies the specific cause first.
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P0118 and Your MOT
A stored P0118 fault code will cause your car to fail its MOT. The engine management light will be illuminated during the test — an automatic failure under current MOT standards. Even if the light temporarily clears, the code remains in ECU memory and can be read by testers.
Get the fault diagnosed and repaired first, then have the code cleared and confirm the light stays off before booking your MOT.