U0131: Lost Communication With Power Steering Control Module A
What to do
The steering still works — you can steer the car — but the power assistance has gone, so it will feel very heavy.
The heaviness is worst when you are barely moving and much milder once you are rolling, so if this happens while driving, keep going gently to somewhere safe rather than stopping in an awkward place. Parking it will take real effort; take wide, slow lines and avoid turning the wheel while stationary.
Think about whether anyone else who drives the car will physically manage it before they take it out.
Ask for the battery, its terminals and the main earth connections to be tested before anything expensive is discussed. Electric steering draws an enormous current in bursts, so a weak battery or a corroded connection is a genuine and common cause — and on many cars the steering motor is built into the rack, which makes the alternative a very large bill.
What this code means
The power steering control module has stopped being heard from. The general reasoning is at U0100, and the difference from U0130 is that this module provides the assistance rather than grading it.
Losing it usually means losing assistance altogether, and the change is abrupt rather than gradual. Electric power steering has no reservoir, no belt and no hydraulic inertia — when the motor stops, the help stops, in an instant.
The car remains steerable. The steering rack is mechanically connected to the front wheels and always has been; the motor adds force to what the driver applies. What changes is how much force that is, and at low speed it is a great deal — parking an average car with the assistance gone is genuinely hard physical work. At road speed the difference is far smaller, because the self-centring forces are lower and the wheels are rolling rather than scrubbing.
That asymmetry is the useful thing to tell a driver: it is manageable while you are moving and heavy when you are not. Which also means the failure is least dangerous where it feels most dramatic.
One cause deserves naming ahead of the module: the 12 volt supply. Electric steering draws a large current in bursts — hundreds of amps at full lock — so it is unusually sensitive to a tired battery, a corroded earth or a poor main connection. A battery that is merely weak can take the steering assistance out, and it is a much cheaper finding than a steering rack, which on many vehicles is what the motor is built into.
Likely causes
Start here
- Low system voltage · easy
- Corroded earth connection · easy
- Failed power or earth supply to the module · moderate
- Damaged data bus wiring · moderate
Less common
- Blown fuse or failed supply · easy
- Failed power steering control module · specialist
Symptoms
Components involved
Information, not instruction
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