P0573 — Brake Switch « A » Circuit High

The diagnostic trouble code P0573 indicates that the vehicle’s engine control unit (ECU) has detected a high voltage condition in the brake switch circuit, specifically the « A » circuit. This switch is essential for various safety and operational functions, including the activation of the brake lights and assisting systems like cruise control. It’s important to address this code promptly to ensure proper vehicle operation and safety. Note that labels and designations for this circuit may vary slightly between vehicle manufacturers.

  • System affected: Brake switch circuit
  • Severity: Moderate — requires diagnosis and repair to prevent safety issues
  • Main symptoms: Brake warning light activation, cruise control malfunction, possibly limited vehicle operation
  • Driveability: Limited — vehicle can usually be driven but with caution and pending repair

Manufacturer variations for trouble code P0573

Different vehicle manufacturers may label or identify this fault using varied codes or terminology, reflecting their specific diagnostic protocols and wiring designations. While the core issue remains the same—an abnormal voltage signal in the brake switch circuit—recognition of label variations can aid in correct troubleshooting.

  • Ford / Lincoln: U213A, U213B
  • Volkswagen / Audi / Skoda / SEAT: 01435
  • Toyota: P0573 (sometimes coupled with other codes related to brake system)
  • Honda: C39, C57
  • BMW: 2A9D, 2A9C

What does trouble code P0573 mean?

This code signals that the ECU detects a high voltage in the Brake Switch « A » circuit. The brake switch acts as a sensor that tells the vehicle when the brake pedal is pressed or released. When functioning correctly, it provides a specific voltage range to the ECU indicating pedal position. However, if the voltage exceeds expected levels—possibly due to wiring issues, faulty switch, or electrical interference—the ECU flags this as an abnormal signal, causing the P0573 trouble code to set.

In simpler terms, the vehicle’s brain notices an unusual, excessively high electrical signal coming from the brake pedal sensor. This could be caused by a problem in the wiring, the switch itself, or other electrical components connected to this circuit.

The trouble code typically appears during routine checks with an OBD-II scanner, often accompanied by warning lights or malfunctions in related systems.

Severity and risks of trouble code P0573

The P0573 code does pose some safety considerations. A malfunction in the brake switch can lead to issues like inoperable brake lights, which are safety-critical signals to other drivers. Additionally, some vehicle functions—such as cruise control deactivation or auto hold features—may malfunction if the ECU perceives inconsistent brake switch signals.

While the car may still be drivable, ignoring the problem could lead to confusion for other road users and potential legal issues regarding functioning brake lights. Therefore, the severity is considered moderate. Addressing this issue promptly is strongly recommended to prevent further electrical or safety-related complications.

**Can the vehicle be driven?** — Limited, depending on vehicle systems. It is safe to drive for short distances but with caution until repairs are completed.

Symptoms of trouble code P0573

Recognising the symptoms associated with this trouble code can help identify an issue early. Common symptoms include:

  • Illumination of the brake warning light or other related warning indicators on the instrument cluster
  • Cruise control not engaging or disengaging unexpectedly
  • Inconsistent or non-functioning brake lights
  • Erratic operation of brake-related features, such as auto hold or parking assist
  • Possible difficulty in starting the vehicle, if related to brake switch signals

Most likely causes of trouble code P0573

Understanding what leads to this trouble code can streamline diagnosis and repair. The causes are often electrical or sensor-related, and typically involve issues in the brake switch circuit.

  1. Faulty Brake Switch: The switch itself might be defective, worn out, or stuck, causing abnormal voltage signals.
  2. Wiring or Connector Problems: Damaged, corroded, or loose wiring or connectors in the circuit can generate high voltage readings or intermittent signals.
  3. Short Circuits or Grounding Issues: A short circuit or poor grounding within the brake switch circuit can lead to excessive voltage levels.
  4. ECU or Module Malfunction: Rarely, the ECU or related module may incorrectly interpret signals due to internal faults, though this is less common.
  5. Other Electrical Interference: External electrical noise or interference can sometimes cause false readings in the circuit.

How to diagnose trouble code P0573

Diagnosing P0573 involves methodical checks to identify the root cause. Always ensure safety precautions are in place before handling electrical components.

  1. Visual Inspection: Examine the brake switch, wiring harness, and connectors for visible damage, corrosion, or loose connections.
  2. Test Brake Switch Operation: Using a multimeter, verify the switch’s continuity and proper operation when pressing and releasing the brake pedal.
  3. Check Wiring and Connectors: Ensure all wiring goes to the correct terminals, is undamaged, and has solid connections.
  4. Monitor Live Data: Use a diagnostic scan tool to view real-time voltage signals from the brake switch circuit during pedal actuation.
  5. Conduct Continuity and Voltage Tests: Measure circuit resistance and voltage levels at various points to identify anomalies or shorts.
  6. Inspect Grounds: Confirm that grounding points for the circuit are clean, secure, and functional.
  7. Check for Related Codes: Look for additional fault codes that may provide clues or point to related issues.

Possible repairs for trouble code P0573

Based on the diagnostics, repairs may vary in complexity. Many are straightforward, but some might require professional assistance.

  • Replace the Brake Switch: If the switch is defective, replacing it with a new OEM-quality part is the most direct fix. This is a basic repair typically suited for DIY enthusiasts with basic tools.
  • Repair or Replace Damaged Wiring: Fix or replace damaged wiring or connectors. This task may involve soldering or connector replacement, often best performed by professionals.
  • Address Grounding Issues: Clean and tighten ground connections to ensure proper electrical flow. Usually a simple repair.
  • Correct Short Circuits: Identify and eliminate any shorts in the circuit, which may involve wiring repairs or replacement.
  • Update or Reprogram ECU: If internal ECU issues are suspected, software updates or reprogramming by a professional OEM dealer may be necessary.

Vehicles commonly associated with trouble code P0573 in Europe

While this trouble code can affect various makes, some vehicle brands are more frequently involved, especially those with complex electrical systems or known issues in their brake circuit wiring.

Typically, P0573 appears in a range of European vehicles, notably:

  • Volkswagen Group: Volkswagen, Audi, Skoda, SEAT
  • BMW
  • Mercedes-Benz
  • Peugeot
  • Citroën

Specific engine families or models may vary, but most issues involve common electrical components linked to the brake system.

Frequent mistakes with trouble code P0573

Diagnosing and repairing P0573 can sometimes be complicated by common pitfalls. Avoiding these mistakes can promote more accurate repair and prevent unnecessary costs.

  • Assuming the fault is with the ECU first without inspecting wiring or the switch: Many issues are wiring or switch faults, not ECU malfunctions.
  • Overlooking visual inspection: Damaged connectors or wiring are often quick to identify and fix.
  • Replacing parts without proper testing: Blind replacement can lead to unnecessary expenses; always verify the cause.
  • Ignoring related systems or codes: Additional fault codes can provide crucial clues.
  • Failing to secure safety precautions: Handling electrical components improperly can pose risks; always disconnect the battery before extensive repairs.

FAQ — trouble code P0573

Can this code disappear on its own?

Generally, P0573 is unlikely to clear automatically without repair. It may reset temporarily after fixing the cause but often returns if the underlying fault persists.

Can I keep driving?

Driving with this code is possible but not recommended. The issue can cause safety concerns, especially if brake lights or safety systems are affected. Limit driving until the problem is repaired.

Why does the code return after clearing?

The code reappears if the underlying fault—such as wiring damage or a defective brake switch—remains unresolved. Proper diagnosis and repair are essential to prevent recurrence.

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