Coolant Temperature Sensor
2011 Ford F-150 · 5.0L V8 Coyote
Sensor Type
thermistor
Waveform Type
dc-variable
Location
Driver side of engine block, near thermostat housing at front of engine below intake manifold
Pins
2-pin connector
Timebase
10s/div for warmup analysis
Voltage Scale
1V/div
Trigger
Not applicable for DC signal
Wiring
Gray/Red wire (signal to PCM pin 91) and Black wire (sensor ground)
Expected Voltage Range
At Idle
0.4V to 0.9V
At Higher RPM
0.3V to 0.7V
Expected Pattern
Smooth declining DC voltage as engine warms, negative temperature coefficient thermistor with 5V reference
Known-Good Waveform
Cold engine (68°F) should read approximately 2.5-3.0V, dropping smoothly to 0.5-0.7V at normal operating temperature (195-210°F). The voltage decline should be gradual and consistent without jumps or erratic fluctuations during warmup period of 8-12 minutes.
Common Failure Patterns
Voltage stuck at 4.8-5.0V regardless of temperature
Cause: Open circuit in sensor or wiring, broken sensor element
Voltage reads near 0V or jumps erratically
Cause: Short to ground in wiring or failed sensor with internal short
Diagnostic Tips
Compare ECT reading to IAT at cold start - they should be within 10°F. On Coyote engines, a failing ECT can cause rough cold start and delayed VCT engagement. Verify 5V reference at sensor connector with sensor unplugged.
Related Diagnostic Trouble Codes
P0115P0116P0117P0118P0119
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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