P0117
ECT Sensor Circuit Low Input
medium
i Description
The Engine Coolant Temperature sensor is reporting an implausibly low voltage, suggesting an extremely high temperature to the ECU. This is usually a wiring or sensor fault rather than actual overheating.
? Common Causes
- Short circuit in ECT sensor wiring
- Faulty ECT sensor (internal short)
- Corroded connector
! Symptoms
- Check engine light
- Cooling fans running constantly
- Lean fuel mixture
- Temperature gauge reading very high
# Diagnostic Steps
- Verify actual engine temperature with infrared thermometer
- Test ECT sensor resistance
- Check for wiring shorts
- Replace sensor if shorted internally
⚙ Typical Fix
Replace the ECT sensor or repair shorted wiring.
Parts Needed
ECT sensor
Estimated Cost
$30-$200
↔ Related Codes
Q Frequently Asked Questions
Check actual temperature first. If the engine is not truly overheating, it is safe to drive. The fans may run all the time, which is annoying but not harmful.
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