Code Definition

P1115 — Engine Coolant Temperature intermittent High or Low

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: GM

About P1115

P1115 is a manufacturer-specific powertrain diagnostic trouble code recorded for GM vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1115 is stored, the module has detected a signal or supply voltage lower than the expected operating range; and a signal or supply voltage higher than the expected operating range.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1115 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The engine coolant temperature sensor is a negative temperature coefficient thermistor fitted in the coolant jacket and supplied with a 5V reference through a pull up resistor inside the Powertrain Control Module, so its resistance falls as coolant temperature rises and the signal voltage falls with it, typically from around 4.5V on a cold engine to under 1.0V at full operating temperature. The PCM uses this reading for cold start enrichment, ignition timing, idle speed, cooling fan control, torque converter clutch scheduling, and entry into closed loop fuel control, so it influences almost ev...

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