P0118 — High input from ECT sensor. ECM sees sub-zero coolant temp and over-fuels. Dash gauge may read at zero

What it means

Common causes

• Break in ECT ground wire
• Signal wire shorted to supply
• Internal open in the sensor's thermistor
• Poor connector contact — common after engine bay washing
• Corroded wiring
• Try replacing the ECT sensor first — cheap test

How to diagnose

1. 01

   Read all stored and pending codes with an OBD-II adapter — get the full picture, not just the one code.

2. 02

   Capture freeze-frame data (RPM, coolant temperature, engine load) at the exact moment the code triggered.

3. 03

   Inspect the named subsystem with our app's AI explanation — get vehicle-specific causes for your make, model and year.

Related codes

• P0117 Low input from Engine Coolant Temperature (ECT) sensor. ECM thinks the engine is running at 140°C and activates cooling aggressively
• P0125 Coolant temperature isn't rising fast enough to enter closed-loop fuel control. Engine takes forever to warm up, ECM stays in enriched open-loop — fuel economy tanks
• P0128 Coolant temperature hasn't reached normal operating range (87–92°C) in the expected time. Engine warms slowly or never fully warms — gauge stalls at 60–70°C
• P0121 Throttle/Pedal Position Sensor/Switch 'A' Circuit Range/Performance
• P0122 Low input from Throttle Position Sensor (TPS). Pedal is pressed but sensor reports zero — ECM enters limp mode
• P0113 High input from IAT sensor. ECM interprets it as sub-zero intake air and floods the mixture