P080CUpshift/Skip Shift Solenoid Control Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- GM's skip-shift (CAGS) on manual gearboxes such as the T56 and TR6060 uses an engine-module solenoid that, at light load, blocks the way from 1st into 2nd so the driver shifts 1 to 4; the 1-4 lamp shows it (P0804). The engine module drives the solenoid with a low-side driver; P0803 is the open circuit. P080C means the control line is shorted to ground: with the driver off it should sit at battery voltage through the coil but reads low (GM: 0.5 Ω or less to ground). GM checks it from 9 V (2015/16: 11–32 V) and above 250 rpm, 5 of 6 samples of 250 ms, type B with the MIL after two trips; the 2019 LT5 uses 20 of 25 samples and type A, one trip. In the 2015/16 tables P080C also covers an open circuit. A low-side short keeps the solenoid energized, so the lockout may stay active.
- What you may notice
- Check engine lamp
- 1-4 lockout permanently active or not working
- 1-4 lamp possibly unrelated to the lockout
- Likely causes
- LikelyControl wire chafed through to ground at gearbox or frame
- PossibleSolenoid coil shorted to its housing
- PossibleConnector corroded or water ingress
- PossibleOlder GM modules: circuit open or solenoid unplugged
- RareEngine module driver faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.