P0571 — Brake Switch « A » Circuit

Overview of the code

The diagnostic trouble code P0571 indicates a problem with the Brake Switch « A » circuit. Essentially, this code is triggered when the vehicle’s Electronic Control Unit (ECU) detects an abnormal signal or fault in the switch responsible for monitoring the brake pedal position. The brake switch is a critical component that informs the ECU whether the brake pedal is pressed, which is essential for engine control and safety systems.

Note: Labels for this code can vary depending on the manufacturer, as different OEMs may label the fault differently within their diagnostic systems.

Fast Facts

System affected: Brake Pedal Switch / Brake System
Severity: Moderate; safety-related system
Main symptoms: Brake warning light, shift interlock issues, cruise control deactivation
Driveability: Limited — Vehicle may still be drivable but with safety or functionality issues

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Manufacturer variations for trouble code P0571

Different vehicle manufacturers may assign different labels or code numbers for similar issues related to the brake switch circuit. It is common to find manufacturer-specific codes or descriptions in their proprietary diagnostic systems, but the P0571 code is a standard OBD-II generic code used across many brands.

Some known label variations include:

Ford: P0571 — Throttle/Pedal Position Sensor/Switch « A »
Volkswagen / Audi: 01236 — Brake Light Switch Circuit
BMW: 5E41 — Brake switch signal abnormal
Mercedes-Benz: 2465 — Brake pedal switch malfunction

*Note: Always refer to the manufacturer’s specific repair manual or diagnostic tool for exact labelings.*

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What does trouble code P0571 mean?

In simple terms, the P0571 code signals that the vehicle’s ECU has detected an issue with the brake switch « A ». This switch is normally located near the brake pedal and acts as an electronic or mechanical sensor to signal when the brake pedal is pressed.

The ECU constantly monitors this circuit for expected signals or voltage levels. If it detects a discrepancy, interruption, or abnormal signal, the code is set. Typically, this fault arises when the switch fails, wiring is damaged, or the signal is inconsistent.

It often appears when the brake pedal switch signal does not match the expected state during vehicle startup, press, or operation, potentially impacting safety or vehicle electronics that rely on this input.

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Severity and risks of trouble code P0571

The P0571 fault is considered moderate in severity. Since it involves a safety-critical component—the brake pedal switch—there are important safety implications. The primary risk is that the vehicle’s brake systems or driving aids might not function correctly, or the vehicle’s warning lights may stay on, creating confusion for the driver.

Possible risks include:

Inability to disengage cruise control or speed limiter systems safely
Issues with the shift lock system, preventing the vehicle from shifting out of park
Failure of brake warning lights to operate, reducing awareness of brake system status
Potential for unintended vehicle movement if the brake pedal signals are not correctly received

**Conclusion:** The vehicle can often still be driven with this fault, but it is essential to address the issue promptly to avoid safety risks or further damage.

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Symptoms of trouble code P0571

The manifestation of the P0571 code can be subtle or obvious, depending on the severity and specific vehicle systems affected. Common symptoms include:

The brake warning light on the dashboard illuminates
Difficulty or inability to shift gears due to shift interlock system activation
Interruption or deactivation of cruise control functionality
Erratic or inconsistent brake pedal response or sensor signals
ABS or other braking system warning lights may illuminate if related systems detect anomalies
Noticeable delay or abnormality when pressing the brake pedal, such as unresponsiveness or a stiff pedal feel

Any combination of these symptoms should prompt a thorough diagnostic process to confirm the fault source.

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Most likely causes of trouble code P0571

Although the exact cause can vary, the most common reasons for the P0571 code include:

The introductory issues revolve around electrical communication and sensor integrity. Most frequently, the causes are:

Failed or faulty brake switch — The switch itself is worn, broken, or misaligned, failing to correctly signal when brakes are pressed.
Wiring problems — Damaged, corroded, or disconnected wires leading to or from the brake switch, causing intermittent or absent signals.
Loose connections — Faulty or loose connectors at the brake switch or ECU connection points.
Electrical interference or short circuits — External factors that disrupt or corrupt the circuit signals.
ECU or control module issues — Rare but possible, if the ECU misinterprets signals or malfunctions internally.

Addressing the most common causes first, such as the switch itself and wiring integrity, will usually lead to an efficient repair process.

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How to diagnose trouble code P0571

To accurately identify the root cause of the P0571, follow these generic diagnostic steps:

Visual Inspection: Check the brake pedal switch and wiring for obvious damage, corrosion, or disconnection. Ensure that the switch is correctly aligned and engaged.
Check the relevant fuses and relays: Ensure that power supply to the brake switch circuit is intact.
Use a diagnostic scan tool: Read live data from the ECU to observe the brake switch status indicator when pressing and releasing the brake pedal.
Test continuity: Use a multimeter to verify the circuit continuity at the switch and wiring harness.
Inspect the switch itself: If accessible, test the switch for proper operation or replace if faulty.
Clear codes and retest: After repairs, clear the fault codes and test drive to confirm the fault has been resolved.

Always follow the manufacturer’s specific troubleshooting procedures if available.

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Possible repairs for trouble code P0571

Once the causes have been identified, the appropriate repairs generally involve restoring proper circuit function or replacing defective components. Common repair options include:

Replacing the brake switch: Usually a straightforward, low-cost repair suitable for a basic repair job. Requires some mechanical work to access and replace the switch.
Repairing or replacing wiring: Fixing damaged wires, reconnecting loose plugs, or replacing damaged wiring harness segments. This is typically a job for an experienced technician.
Cleaning or correcting connectors: Ensuring all electrical connectors are securely seated, free of corrosion, and making good contact.
Addressing circuit or ECU issues: Rarely, the ECU may need to be reprogrammed, re-flashed, or replaced, which requires professional diagnostics and software tools.

**Note:** Always consult the manufacturer’s recommendations before replacing parts, and consider performing a calibration or relearn procedure if applicable.

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Vehicles commonly associated with trouble code P0571 in Europe

This code may appear across a wide range of vehicle makes, especially those with electronic brake systems. In Europe, common brands include:

– Volkswagen Group (Volkswagen, Audi, SEAT, Skoda)
– Ford
– BMW
– Mercedes-Benz
– Peugeot
– Citroën

While the presence of this code is not confined to specific engine families, it is often linked to models with advanced driver assistance systems or electronically controlled braking.

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Frequent mistakes with trouble code P0571

Diagnosing and repairing this fault can be hampered by common errors, which include:

Replacing parts without proper diagnosis: For example, switching the switch without verifying wiring or circuit integrity.
Ignoring wiring and connector issues: Overlooking damaged or loose wiring, which can cause recurrent faults.
Using unqualified or incorrect repair parts: Installing incompatible or low-quality replacements that don’t meet OEM standards.
Overlooking the ECM/ECU software status: Failing to verify if software updates or reprogramming are necessary after repair.
Misinterpreting live data signals: Drawing conclusions without verifying actual switch operation during testing.

Following systematic diagnostic procedures minimizes errors and ensures long-term reliability.

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FAQ — trouble code P0571

Q: Can this code disappear on its own?
A: It is unlikely for the P0571 code to resolve spontaneously. Usually, the fault persists until the underlying issue is addressed, although temporary circuit glitches may cause intermittent faults.

Q: Can I keep driving?
A: The vehicle may still be drivable with this fault, but it is not advisable to ignore the problem, particularly if safety features or transmission controls are affected. Professional diagnosis is recommended to prevent potential safety issues.

Q: Why does the code return after clearing?
A: The underlying circuit problem, such as a faulty switch or damaged wiring, is not fixed, so once the system resets, the fault reappears. Thorough inspection and repair are necessary to prevent recurrence.