Code Definition

P1117 — Engine Coolant Temperature Below Minimum Voltage/254 F

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

About P1117

P1117 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 P1117 is stored, the module has detected a signal or supply voltage lower 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.

P1117 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

This DTC sets when the Engine Control Module (ECM) detects that the Engine Coolant Temperature (ECT) sensor signal voltage has dropped below a calibrated minimum threshold, typically indicating an unrealistically high temperature (e.g., 254°F or higher). The ECT sensor is a negative temperature coefficient (NTC) thermistor, where resistance decreases as temperature increases. A voltage below the minimum threshold suggests a short to ground or a failed sensor that falsely reports excessive engine temperature.

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