Code Definition

P1185 — Engine Temperature Sensor circuit

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

About P1185

P1185 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 P1185 is stored, the module has detected a sensor-related fault — the reported value from the named sensor is out of spec.

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.

P1185 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 temperature sensor is a negative temperature coefficient (NTC) thermistor that the Engine Control Module (ECM) supplies with a 5V reference through an internal pull up resistor. As the engine warms the sensor resistance falls and the voltage the ECM sees on the signal wire drops, typically from around 4.5V when cold to below 1.0V at full operating temperature. DTC P1185 is set when the ECM detects that the signal voltage on the engine temperature sensor circuit is outside the plausible range, is stuck, or does not respond as expected, meaning the ECM can no longer trust the temperat...

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