Code Definition

P0939 — Hydraulic Oil Temperature Sensor Circuit Low Input

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0939

P0939 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0939 is stored, the module has detected a signal or supply voltage lower than the expected operating range; and 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.

Because P0939 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The P0939 fault code is set when the control module detects a low input condition in the hydraulic oil temperature sensor circuit. This circuit plays a crucial role in monitoring the temperature of hydraulic oil in systems such as the transmission or power steering. A low input condition typically indicates that the signal from the hydraulic oil temperature sensor to the control module is below the expected range. This could be due to issues like a malfunctioning sensor, a short circuit, or problems with the wiring or connectors. Low input can lead to inaccurate temperature readings, potential...

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