C059APower Steering Control Module - Rear Missing Calibration
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- C059A concerns active rear-axle steering: its control module lacks the calibration it needs to position the rear wheels. Systems like ZF's AKC turn the rear wheels by a few degrees with an electrically driven spindle, either through one central actuator or one per wheel. A Magna patent shows what has to be calibrated: a coarse absolute travel sensor and a fine rotor sensor are referenced to the geometric centre between both mechanical end stops, and these values are stored so the actuator can return to straight-ahead. Without them the module cannot hold the rear wheels centred and disables rear steering. No maker documents C059A publicly. GM names the part K92 Rear Power Steering Control Module; on the 2024 Hummer EV it stopped working after vehicle-wide programming until authentication was repeated (PIT6350), logged as U3000/U1961/U1962.
- What you may notice
- Rear steering warning in the cluster and rear wheel steering inactive
- Larger turning circle and changed handling at speed
- Steering wheel slightly off centre on straight roads
- Likely causes
- LikelyRear steering module or actuator replaced without centre calibration
- PossibleProgramming or setup after a software update not completed
- PossibleSuspension or alignment work requiring a new rear steering zero point
- RareLow 12 V supply interrupting the calibration routine
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €100 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.