What P0999 means
Shift Solenoid F Control Circuit High
How to diagnose
- Read freeze frame data. When P0999 set, your ECU snapshotted every sensor at that moment. This tells you what the car was doing when the fault triggered — RPM, load, coolant temp, throttle position, fuel trims. Almost always enough info to figure out the cause without further testing.
- Check for related codes. If you have P0999 plus other codes, fix the earliest one in the chain first — a single root cause often triggers multiple codes.
- Cheap fixes first. For most codes, the order is: inspect connectors + wiring (free), check for vacuum leaks (cheap), replace sensor (moderate), replace mechanical part (expensive). Follow that ladder before dropping money on parts.
Manufacturer-specific descriptions
Different manufacturers use P0999 for slightly different failure modes:
| BMW | Shift Solenoid "F" Control Circuit High P0A00 Motor Electronics Coolant Temperature Sensor Circuit P0A01 Motor Electronics Coolant Temperature Sensor Circuit Range/Performance P0A02 Motor Electronics Coolant Temperature Sensor Circuit Low P0A03 Motor Electronics Coolant Temperature Sensor Circuit High P0A04 Motor Electronics Coolant Temperature Sensor Circuit Intermittent P0A05 Motor Electronics C... |
| MITSUBISHI | Shift Solenoid F Control Circuit High |
| NISSAN | Shift Solenoid F Control Circuit High |
Read P0999 on your own car
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