Code Definition

P0731 — Gear 1 Incorrect ratio

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

About P0731

P0731 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.

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 P0731 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 P0731 fault code is set when the Transmission Control Module (TCM) detects that the ratio of gear 1 in the transmission is not functioning within the manufacturer's specified range. This code indicates a discrepancy between the expected and actual gear ratios, which can affect the vehicle's ability to operate in first gear. The issue could stem from various factors, including mechanical problems within the transmission, issues with the transmission fluid, or sensor malfunctions. The incorrect ratio may lead to noticeable symptoms such as slipping in first gear, poor acceleration, or failur...

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