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C0559 — Power Steering Control Module Rangeperformance Rear

Generic OBD-II · all makesChassis

OBD-II code C0559 indicates that the Power Steering Control Module (PSCM) has detected an out-of-range or performance issue with the rear power steering system. This typically means the system is not responding as expected to commands or sensor inputs, potentially affecting steering assist.

Symptoms

What causes it — most likely first

1. Faulty rear power steering motor or actuator

The rear steering actuator or motor may fail internally, causing incorrect or no response to control signals. This is a common failure point in systems with active rear steering.

2. Wiring or connector issues in the rear steering system

Damaged, corroded, or loose wiring or connectors between the PSCM and the rear steering actuator can cause signal loss or erratic performance.

3. Failed rear steering position sensor

The sensor that monitors the position of the rear steering system may provide incorrect or no feedback to the PSCM, triggering the code.

4. Low system voltage or poor electrical supply

Insufficient voltage to the PSCM or rear steering components can cause performance issues, often due to a weak battery, bad alternator, or poor ground connections.

5. Mechanical binding or obstruction in the rear steering system

Physical obstructions, misalignment, or binding in the rear steering linkage or actuator can prevent proper operation and trigger the code.

6. Faulty Power Steering Control Module (PSCM)

While rare, the PSCM itself may fail internally, causing incorrect interpretation of sensor data or improper commands to the rear steering system. This should be considered only after all other causes are ruled out.

How it's diagnosed

  1. Scan for additional codes in the PSCM and related systems (e.g., ABS, chassis) to identify correlated issues.
  2. Inspect wiring and connectors between the PSCM and rear steering actuator for damage, corrosion, or loose connections.
  3. Test the rear steering position sensor and actuator for proper operation using a scan tool or multimeter, following manufacturer specifications.
  4. Check system voltage at the PSCM and rear steering components to ensure adequate power supply and ground connections.
  5. Perform a mechanical inspection of the rear steering system for binding, obstructions, or misalignment.
  6. If all other causes are ruled out, test or replace the PSCM, but only as a last resort due to the rarity of module failure for this code.

Code facts & related codes

SystemChassis
StandardizationSAE generic — identical on every make
Related codesC0550 — Vacuum Sensor B Circuit HighC0551 — Longitudinal Acceleration Sensor CircuC0552 — Longitudinal Acceleration Sensor RangeC0553 — Longitudinal Acceleration Sensor CircuC0554 — Longitudinal Acceleration Sensor CircuC0555 — Left Front Wheel Speed Sensor Incorrec

Frequently asked

Is the Power Steering Control Module (PSCM) usually the cause of C0559?

No, the PSCM is rarely the cause of C0559. Most failures stem from the rear steering actuator, wiring, or sensors. Replacing the PSCM should only be considered after all other potential causes have been thoroughly tested and ruled out.

Can I drive with C0559 active?

Driving with C0559 may result in reduced or erratic power steering assist, making the vehicle harder to steer, especially at low speeds. It is recommended to diagnose and repair the issue promptly to avoid potential safety risks.

Why does my steering feel heavy or loose with this code?

The code indicates the rear steering system is not performing as expected, which can affect overall steering feel. The system may default to a fail-safe mode, reducing or disabling power assist to prevent further damage.

Will resetting the code fix the issue?

Resetting the code without addressing the underlying cause will likely result in the code returning. The issue must be diagnosed and repaired to resolve the problem permanently.