Upshift/Skip Shift Solenoid Control Circuit
What it means
P0803 means the control module found a fault in the circuit for the upshift (skip-shift, or CAGS) solenoid. On some manual-transmission cars this solenoid forces a 1-to-4 upshift under light load to save fuel. A circuit fault disables the feature and lights the check-engine lamp, but the car drives normally. It's often caused by wiring, the solenoid itself, or an aftermarket skip-shift eliminator.
Can I keep driving? This affects the skip-shift (CAGS) feature on manual cars, not normal driving — you can drive as usual; you just may not get the forced 1-4 upshift, and the light stays on.
Common symptoms
What you'll notice
- Check-engine light on
- Skip-shift (forced 1-4 upshift) feature no longer works
- Possible skip-shift indicator lamp behavior
Common causes
Most likely first
- Faulty skip-shift (upshift) solenoidLikely
- Wiring or connector fault in the solenoid circuitCommon
- Blown fuse or faulty relay for the circuitCommon
- Aftermarket skip-shift eliminator installed (disables the solenoid)Less often
- Powertrain/transmission control module faultLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and confirm the circuit fault.
- Check whether an aftermarket skip-shift bypass has been installed.
- Inspect the solenoid wiring, connector, fuse, and relay.
- Measure the solenoid resistance against spec; replace if out of range.
- If wiring and solenoid are good, suspect the control module. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0803?+
Can I just clear P0803?+
Related codes
Often seen with P0803
Read & clear P0803 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.