P0635Power Steering Control Circuit
- Generic OBD-II code · Powertrain
- Can trigger limp mode
- How the car detects it
- P0635–P0637 concern the control or signal circuit between engine module and power steering – depending on the maker the drive of an electro-hydraulic pump or the steering load signal the engine module uses to raise idle. CARB requires power steering components to be monitored only if another diagnostic uses them, so these codes are rare and maker-specific. Mercedes-Benz stores P0635 in the electric steering module itself (no assist after start, software update); no engine module table available to us uses P0635–P0637. P0635 is the general or open-circuit code; output components must be checked for circuit faults, but separate low/high codes (P0636/P0637) are not mandatory. Steering assist may fail or be reduced; without the load signal idle can sag at full lock. The power steering pressure switch family is P0550–P0554.
- What you may notice
- Power steering warning, heavy steering
- Check engine light (depending on the maker)
- Idle drops when steering
- Fault possibly only after engine start
- Likely causes
- LikelyWire or connector between engine module and steering module or pump open or corroded
- PossibleSoftware or calibration fault in the steering module (Mercedes)
- PossibleSteering module or electro-hydraulic pump faulty
- PossibleUndervoltage from weak battery, alternator or poor ground
- RareEngine module faulty
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.