Check Engine Code

P0118

Engine Coolant Temperature Sensor Circuit High Input

Severity: medium DIY difficulty: 1/5 Typical cost: $15–$150

What P0118 means

Counterpart to P0117. ECM is seeing an open circuit or implausibly hot coolant reading from the ECT sensor.

Symptoms

  • Check engine light
  • Cold-start hard / no-start
  • Cooling fans running at low temp
  • Erratic gauge

Likely causes (most common first)

  1. Disconnected ECT connector
  2. Open ECT sensor
  3. Broken signal wire
  4. Corroded pins

Can I keep driving?

Medium — drivable but fix soon

Typical repair cost

DIY fixes can start near $15 (parts only). Shop repairs for P0118 typically run up to $150 depending on the underlying cause and vehicle. Start with the most common cause — Disconnected ECT connector — before throwing parts at it.

Related codes

P0117P0125P0128

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