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DTC codes / C05xx · Brakes, steering and suspension / C0559

C0559Power Steering Control Module Range/Performance – Rear

The power steering control module (PSCM) monitors the rear actuator circuit and has detected that its electrical behavior is outside the expected range or performance window. This means the module cannot reliably command or verify rear steering assist, so it stores code C0559 and may disable the system.

SystemChassis
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaBrakes, steering and suspension

Symptoms you may notice

  • A warning light or message on the dashboard indicating a steering system fault
  • Often no symptoms besides the warning light, especially if the fault is intermittent
  • Reduced or absent rear steering assist, making the vehicle feel less stable in turns
  • The steering system may enter a fail-safe mode with heavier steering effort
  • Intermittent operation of the rear steering feature, such as delayed response or sudden changes in assist

Common causes, most likely first

  1. Damaged or corroded wiring and connectors in the rear steering actuator circuit
  2. Faulty rear steering actuator or its internal position sensor
  3. Power steering control module software or internal hardware fault
  4. Low battery voltage or poor ground connection affecting module performance
  5. Aftermarket accessories or improper electrical repairs interfering with the circuit
  6. Water intrusion or physical damage to the rear steering components

How to diagnose and fix it

  1. Perform a thorough visual inspection of the rear steering actuator wiring and connectors for damage, corrosion, or loose pins
  2. Check battery voltage and ground connections to ensure the power steering control module receives stable power
  3. Use a scan tool to retrieve all stored codes and freeze-frame data, then clear codes and test-drive to see if C0559 returns
  4. Follow the manufacturer's diagnostic flow chart for C0559, which typically includes measuring resistance and voltage on the actuator circuit
  5. Test the rear steering actuator with a bidirectional scan tool to command movement and verify feedback
  6. If the actuator fails testing, replace it and recalibrate the steering system as required
  7. If wiring and actuator are good, suspect the power steering control module and perform pinpoint tests before replacement

Before you replace the steering actuator

  • A common oversight is assuming the actuator is faulty when the real problem is a chafed wire harness near the rear subframe or suspension components.
  • Low voltage from an aging battery can cause the power steering control module to set false range/performance codes without any actual component failure.
  • The code can be set by a software glitch in the control module, so check for technical service bulletins and software updates before condemning hardware.
  • Aftermarket electrical accessories tapped into the rear steering circuit can introduce noise that triggers this code, so inspect for non-factory wiring.
  • The rear steering actuator may only fail under specific temperature or load conditions, so intermittent codes require extensive test-driving with live data monitoring.

Can I keep driving with C0559?

If the warning light is on and you notice reduced steering assist, drive cautiously and avoid high-speed maneuvers; it is safe to drive to a repair shop but not to ignore the issue long-term. If the steering feels unpredictable or heavy, stop driving and seek professional diagnosis immediately.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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