Engine Coolant Temperature Sensor Circuit Intermittent Low Voltage (GM)
What does P1114 mean?
The P1114 code means the vehicle's onboard diagnostic system has detected: Engine Coolant Temperature Sensor Circuit Intermittent Low Voltage (GM). This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Engine runs rich when cold
- Poor fuel economy
- Cooling fans running at incorrect times
- Hard starting in cold weather
Probable Causes (Ranked by Likelihood)
- Faulty engine coolant temperature (ECT) sensor Very High
- Short to ground in ECT sensor wiring High
- Corroded ECT sensor connector Moderate
- Coolant leak causing low coolant around sensor Moderate
- PCM internal circuit failure Low
Step-by-Step Diagnostic Procedure
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Read ECT sensor temperature on a scan tool and compare to actual engine temperature
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Inspect the ECT sensor connector for corrosion, especially green or white buildup
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Measure ECT sensor resistance at known temperatures
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Check for coolant leaks near the ECT sensor location
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Test the wiring between the ECT sensor and PCM for short to ground
Frequently Asked Questions
What does P1114 mean on a GM vehicle?
P1114 means the engine coolant temperature sensor is intermittently reporting a lower voltage than expected. This makes the PCM think the engine is hotter than it actually is, affecting fuel delivery and fan operation.
Can a bad thermostat cause P1114?
A bad thermostat will not directly cause P1114, as this code specifically relates to an electrical fault in the ECT sensor circuit. However, a stuck-open thermostat can cause a separate P0128 code.
Where is the ECT sensor on GM trucks?
On most GM trucks with V8 engines, the ECT sensor is located near the front of the engine, typically threaded into the intake manifold or cylinder head near the thermostat housing.