Applicable Systems
OBD-II
Symptoms
ECT sensor signal indicates coolant temperature above 140C (short circuit); false overheating warning.
Possible Causes
- ECT sensor signal wire short to ground
- ECT sensor internal short
- Connector water intrusion
Troubleshooting Steps
- Step 1: Check ECT signal wire for short to ground
No short to ground - Step 2: Inspect connector for moisture
Connector dry - Step 3: Measure sensor resistance (should be 200-300 ohm at 80C)
Resistance within range - Step 4: Replace ECT sensor if resistance too low
New sensor resistance normal - Step 5: Clear code and verify temp reading
ECT reads normal operating temp
How to Reset
Clear with OBD-II scanner after repair.
Common Replacement Parts
- ECT Sensor (OEM spec)
Frequently Asked Questions
- Q: What temperature does P0117 indicate?
Signal corresponds to 140C+ which exceeds coolant boiling point. Indicates sensor or wiring fault, not actual overheating.
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Source: SAE J2012 standard DTC list + OBD-II portal
Category: OBD-II
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