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P0999 is a diagnostic trouble code (DTC) for "Shift Solenoid F Control Circuit High". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
The P0999 code identifies a problem in an automatic transmission in the shift solenoid F circuitry and sets the code.
A P0999 code the OBD-II generic code for a problem between the transmission control module and the shift solenoid F control circuit that is high in the ECM or engine control module memory.
What this means is that the operation of the automatic transmission is impaired because the TCM, in shifting through specific gear ratios (activating or deactivating) shift solenoids to operate clutches or breaks in the transmission, encounters a failed check. The TCM will check the function of the solenoid valves by testing resistance and speed sensors. If a check fails, which is what happens when the shift solenoid F control circuit high code appears, it disables that circuit.
There are a few common causes for the P0999 code, and they include:
A P0999 code comes with some frightening symptoms that can include the inability of the driver to be able to engage the vehicle in the "D" mode. They may also be unable to use other gears, or experience very poor acceleration, high engine revving in gear and harsh shifting or poor fuel economy. The vehicle also sets the code.
Diagnostics for the P0999 require a digital ohm meter and the wiring diagram for the vehicle. The circuits will be checked between the TCM and the transmission, and a harness check is done. All connectors are checked and a circuit check will be done as well. The diagnostics also look for ECM faults, open circuits, and a check of the solenoid. If no issues are found, it may be the transmissions internal sub harness and the solenoid.
The P0999 code can easily prevent the vehicle from operating. It may even make it impossible to shift into the "D" gear, or other gears while in operation. The fact that it can also lead to high revving when shifting gears means that there is the serious risk of engine damage or even catastrophic damage during use of the vehicle while it is recording this code.
To address the P0999 code, the following repairs are recommended:
The circuit checks are meant to determine if there is an open solenoid to blame or if there is a break in the sub harness. A final step in repair may be to bench test the solenoid in question using a jumper to ensure it is functional.
YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.