Applicable Systems
OBD-II
Symptoms
ECT sensor signal out of range; ECM cannot determine engine temperature; may cause rich mixture or hard starting.
Possible Causes
- ECT sensor open or short circuit
- Sensor connector corrosion
- ECT sensor internal thermistor failure
Troubleshooting Steps
- Step 1: Check ECT sensor resistance vs temperature chart
Resistance matches chart - Step 2: Inspect ECT sensor connector
Connector clean and tight - Step 3: Check signal wire continuity and shorts
Wiring intact - Step 4: Replace ECT sensor if resistance out of spec
New sensor resistance matches chart - Step 5: Clear code and verify ECT reading
ECT reads 85-95C at operating temp
How to Reset
Clear with OBD-II scanner after sensor replacement.
Common Replacement Parts
- ECT Sensor (OEM spec)
Frequently Asked Questions
- Q: Where is ECT sensor located?
Usually in cylinder head or thermostat housing, immersed in coolant flow path.
Source: SAE J2012 standard DTC list + OBD-II portal
Category: OBD-II