Coolant Temperature Sensor
2020 Toyota Camry · 2.5L I4
Sensor Type
thermistor
Waveform Type
dc-variable
Location
Front of engine block, near thermostat housing on driver side of 2AR-FE/A25A-FKS engine
Pins
2-pin connector
Timebase
1s/div or 5s/div for heat soak testing
Voltage Scale
1V/div
Trigger
Not applicable for DC signal
Wiring
Green wire (signal to ECM pin T18), Brown wire (sensor ground from ECM pin T17)
Expected Voltage Range
At Idle
0.3V to 0.7V
At Higher RPM
0.3V to 0.7V
Expected Pattern
Negative temperature coefficient - voltage decreases as temperature increases, smooth DC voltage with 5V reference
Known-Good Waveform
At cold start (68°F), expect 2.0-2.5V. At normal operating temperature (195-210°F), voltage should be 0.3-0.7V with smooth, gradual decline during warm-up. No sudden jumps or dropouts. Voltage should remain stable at idle with minimal noise (less than 0.05V ripple).
Common Failure Patterns
Voltage stuck at 4.5-5.0V regardless of engine temperature
Cause: Open circuit in sensor or wiring, internally failed thermistor
Related DTCs: P0118
Voltage stuck at 0-0.2V or reads excessively hot
Cause: Short to ground in wiring or internally shorted sensor
Related DTCs: P0117
Diagnostic Tips
Toyota ECT sensors rarely fail internally but connector corrosion is common at the 2-pin gray connector. Verify 4.9-5.1V reference at disconnected sensor. Resistance should be approximately 2.3-2.7kΩ at 68°F.
Related Diagnostic Trouble Codes
P0115P0116P0117P0118P0119
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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