Code Definition

P0999 — Shift Solenoid F Control Circuit High

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

About P0999

P0999 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 P0999 is stored, the module has detected a signal or supply voltage higher 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.

Because P0999 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 P0999 is triggered when the Transmission Control Module (TCM) detects a high voltage condition in the Shift Solenoid 'F' Control Circuit. This high voltage signal implies that the electrical current supplied to the solenoid is exceeding the normal operating range. Such a situation usually indicates a potential short to power in the solenoid circuit, or issues related to the wiring harness or connectors that are leading to excessive voltage being supplied to the solenoid.

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