C00904WD/AWD Power Transfer Unit Actuator
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- Covers the actuator that engages or modulates the power transfer unit (transfer case / front coupling) in a four- or all-wheel-drive system. On demand the controller drives this actuator, typically an electric motor or an electromagnetic/electro-hydraulic clutch operator, to send torque to the secondary axle. This code is set when the actuator circuit is open, shorted, out of range or the actuator does not respond to the command. AWD coupling patents describe electronically controlled clutches actuated by a motor-driven ball-ramp or a gerotor pump to vary torque split between two- and four-wheel-drive modes. A fault can lock the system in one mode or default to two-wheel drive and sets the AWD/4WD warning lamp; braking and ABS are unaffected. The entry follows the SAE J2012 generic definition.
- What you may notice
- AWD/4WD warning lamp on
- Stuck in one drive mode or 2WD default
- Reduced traction on loose surfaces
- Likely causes
- LikelyPTU actuator motor or coil failed
- PossibleOpen or shorted actuator circuit
- RareBinding or worn transfer mechanism
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €250 – €2,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.