P0999
Shift Solenoid F Control Circuit High
Transmission control
Generic OBD-II
Medium
What it means
P0999 means the control circuit for shift solenoid F is reading high voltage, typically an open circuit, high resistance, or a short to power. The transmission may shift harshly, fail to engage the affected gear, or enter limp mode. Inspect the solenoid connector and wiring for an open or a short to power before replacing the solenoid or control module.
Medium
Can I keep driving? Driveable but expect shifting problems — the transmission may hold a gear or enter limp mode, so repair it before it worsens.
Common symptoms
What you'll notice
- Check-engine light on
- Harsh, delayed, or erratic shifting
- Reduced acceleration or a slipping feel
- Possible failure to engage the gear controlled by solenoid F
- Possible limp (fail-safe) mode
Common causes
Most likely first
- Shift solenoid F open or with high resistanceLikely
- Wiring open or shorted to power in the control circuitCommon
- Corroded or loose connectorCommon
- Faulty transmission control module (TCM)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and note which gear/shift is affected.
- Inspect the solenoid connector and wiring for an open circuit or short to power.
- Measure shift solenoid F resistance and compare to spec; replace if open or out of range.
- Repair any damaged wiring or corroded connections.
- If solenoid and wiring are good, have the TCM tested and replaced as a last resort.
FAQ
Quick answers
Is it safe to drive with P0999?+
Short trips are usually okay, but the transmission may shift poorly or drop into limp mode, limiting speed. Get it repaired soon.
Can I just clear P0999?+
It comes back until the solenoid or wiring fault is fixed. Clearing it does not restore the shift function.
Related codes
Often seen with P0999
Read & clear P0999 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX