U0131 - LOST COMMUNICATION WITH POWER STEERING CONTROL MODULE (PSCM)

The Power Steering Control Module (PSCM) is provided with information from sensors, in some cases connected directly to it, while others are sent via the CAN bus network. With these inputs, the module can activate the power steering system with which assistance can be provided only, taking into account that there is a mechanical link to the steering system.

Although many assistance systems are fully electronically controlled, some manufacturers use electronically controlled hydraulic systems and the diagnostic steps to such systems vary depending on the type of communication, wires, and colors.

When the U0131 OBDII diagnostic code is set, it is because communication between the Power Steering Control Module (PSCM) and other control modules on the vehicle has not been established. Usually, this communication is established as the controller area network bus or CAN bus.

How does the U0131 Generic Code work?

As we already established, this code means that the PSCM and other control modules in the vehicle do not communicate with each other. Without the CAN bus, the control modules cannot communicate and your scan tool may not get information from the vehicle, in some cases, it depends on which circuit is at stake.

The PSCM takes input from several sensors, some of which are wired directly to it and some of which are forwarded through a bus communication system. These inputs enable the module to provide an electric power steering system or an electro-hydraulic variable power steering system. These systems assist only, as there is still a mechanical link to the steering system. These auxiliary systems can be either fully electronically controlled or electronically controlled hydraulic systems, depending on the manufacturer’s application.

• Check Engine light comes on.
• Cannot use power steering.

The reasons why the U0131 OBD2 fault code is stored are:

• The positive or negative circuit of the CAN bus network could be shorted.
• There may be a short or open in the CAN bus power or ground circuit.
• The Power Steering Control Module could be faulty.

The difficulty, in this case, depends mainly on the system. Since the system may be an electric power steering system or an electrohydraulic power steering system with variable power steering, the difficulty may be negligible in one system but may be a major safety issue in the absence of power steering in another. The steps to resolve this DTC U0131 OBDII code are:

• Consult the TSB (Technical Service Bulletins).
• With an automotive scanner, you should check if there are other fault codes configured in order to verify if these codes are related to a malfunction of the CAN bus network. Repair these codes first if applicable.
• Inspect the wiring and fuses that supply power to the PSCM. Check them for any damage that would prevent the circuit from performing properly. Repair as necessary.
• Using a multimeter, check that the PSCM power and ground signal is as indicated in the user's manual. If a value is outside the set parameters, proceed to make the appropriate corrections.