Code Definition

P099A — Shift solenoid G circuit malfunction

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

About P099A

P099A 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 P099A is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

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 P099A 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 fault code P099A is set when the Engine Control Module (ECM) or Transmission Control Module (TCM) detects a malfunction within the electrical circuit of shift solenoid G. This solenoid is an integral component of the transmission’s hydraulic system, responsible for controlling the flow of transmission fluid to actuate gear changes. A circuit malfunction suggests an electrical issue such as a short circuit, open circuit, or poor electrical connection, which can impact the solenoid's ability to function properly. This malfunction can lead to issues with gear engagement, shifting patterns, ...

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