Coolant Temperature Sensor (ECT)
2017 Toyota Camry · 2.5L I4
Sensor Type
thermistor
Waveform Type
dc-variable
Location
Front of engine block below intake manifold, near thermostat housing on passenger side
Pins
2-pin connector
Timebase
5s/div or 10s/div for warm-up monitoring
Voltage Scale
1V/div
Trigger
Not applicable - DC signal
Wiring
Green/Black (signal to ECM pin E14) and Brown (sensor ground)
Expected Voltage Range
At Idle
0.3V to 0.8V
At Higher RPM
0.3V to 0.8V
Expected Pattern
Smooth negative temperature coefficient curve - voltage decreases as temperature increases
Known-Good Waveform
Cold engine (68°F) shows approximately 2.5-3.0V, dropping smoothly to 0.3-0.8V at normal operating temperature (195-205°F). Signal should transition smoothly without jumps or steps during warm-up cycle. Resistance should be approximately 2.3-2.5k ohms at 68°F and 200-400 ohms at 195°F.
Common Failure Patterns
Voltage stuck at 4.8-5.0V regardless of temperature
Cause: Open circuit in sensor or wiring, broken internal thermistor element
Voltage at 0V or near 0V when cold
Cause: Short to ground in wiring or failed sensor internally shorted
Related DTCs: P0117
Diagnostic Tips
On 2AR-FE engines, verify ECM ground E01 is clean and tight as poor ground causes erratic ECT readings. The connector is prone to corrosion from coolant seepage; inspect carefully and use dielectric grease during reassembly.
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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