P0571 — Cruise Control/Brake Switch A Circuit Malfunction

Can I drive with P0571 stored?

Yes, cautiously, if the code is historical and the brake lamps, ABS, stability control, and pedal response all work normally. Do not rely on cruise control until the brake switch A circuit has been tested and repaired.

Does P0571 always mean the brake lamps are broken?

No. The brake lamps may operate through another contact or circuit even when the brake switch's circuit A signal is faulty. Lamp operation alone cannot confirm that the signal used by the cruise, powertrain, or ABS controller is correct.

What should be checked first when diagnosing P0571?

Start by confirming the code with an OBD scanner, then inspect the brake switch, its adjustment, connector, and wiring. Brake-switch live data should change consistently when the pedal is pressed and released.

Will replacing the brake switch always clear P0571?

No. A replacement clears P0571 only if the switch was defective. An open wire, poor connector, incorrect adjustment, or faulty controller input can produce the same code and must be ruled out.

Cruise control has become a standard feature on most modern vehicles, and its operation depends on a surprisingly complex web of sensors and control modules working in sync. One of the most critical safety dependencies is the relationship between the cruise control system and the vehicle's braking circuitry. When you press the brake pedal while cruise control is active, the system needs to disengage immediately — that is the job of the brake switch, a small but essential component that tells the cruise control module you are taking manual control. The engine control unit monitors this circuit continuously through the ABS and stability control module. When those self-diagnostics detect an abnormal signal or a fault within the cruise control / brake switch A circuit, the ECU logs trouble code P0571.

P0571 is classified as a powertrain fault code, which means it relates to the engine or transmission management system, even though the actual problem lives in the braking or stability control hardware. The key word here is "malfunction" — this is not a simple open circuit or short circuit code. It means the module's internal self-test of the brake switch A circuit or its surrounding logic has failed in some way. That failure could be a wiring problem, a bad connector, a failed sensor, or in rare cases, a fault inside the module itself. The ECU does not set P0571 based on a single odd reading. It requires the fault condition to appear consistently under specific driving conditions before illuminating the check engine light. This is why the freeze frame data stored alongside the code is so useful — it records engine load, RPM, coolant temperature, and vehicle speed at the exact moment the fault occurred, giving you a reliable starting point for diagnosis.

Understanding what triggers P0571 is the first step toward fixing it correctly and avoiding unnecessary part replacements.

Common symptoms of P0571

• A message on the dashboard indicating that stability control has been disabled or is unavailable
• Unreliable operation of the speedometer or cruise control system, including an inability to set or maintain a cruise speed
• ABS failing to activate during hard braking situations where the system would normally intervene
• Noticeable changes in brake pedal feel, such as altered pulsation or resistance during ABS events
• Illumination of the ABS warning light, the ESC / stability control warning light, or both on the instrument cluster

What causes P0571?

• An internal fault within the cruise control / brake switch A itself, where the switch fails to signal correctly
• Wiring issues such as damaged insulation, broken conductors, or corroded connector pins that disrupt the signal between the sensor and the control module
• A faulty wheel speed sensor that feeds bad data to the ABS module, causing it to flag the cruise control circuit as malfunctioning
• Physical damage to the tone ring, also called a reluctor ring, mounted on the wheel hub — metal debris accumulation or broken teeth on this ring can cause erratic wheel speed readings
• A malfunctioning ABS module or pump motor that fails its internal self-diagnostic check
• A software or programming fault within the control module that governs the cruise control and brake switch logic
• Poor electrical connections at the sensor or module harness that cause intermittent signal loss

How to diagnose P0571

1. Connect a professional-grade OBD2 scanner and confirm that P0571 is stored as an active or pending code. Save the freeze frame data before clearing anything — those recorded conditions are your roadmap to recreating the fault during testing.
2. Review all other stored diagnostic trouble codes. Related codes in the P0500 series or other ABS-related codes often point directly to the failing component, such as a specific wheel speed sensor or the ABS module itself. Also check for any manufacturer technical service bulletins (TSB) that apply to your vehicle's make, model, and year — many P0571 complaints have known factory updates or software flashes.
3. Perform a thorough visual inspection of the wiring harness and connectors associated with the ABS and stability control system. Look for chafed wires, melted insulation near heat sources, corrosion on connector pins, and any connectors that are loose or partially unplugged.
4. If your scanner supports bidirectional controls or module-specific actuator tests, command the cruise control / brake switch A to activate. A component that fails to respond to a direct command is confirmed as defective and should be replaced.
5. Monitor all four wheel speed sensor PIDs on the scanner while driving slowly in a safe location. A faulty sensor will either drop out entirely or display a speed reading that does not match the other three wheels — even small discrepancies can be enough to trigger P0571.
6. With the vehicle raised and the wheel removed, physically inspect each wheel speed sensor and its tone ring. Remove any built-up metal debris from the tone ring and check for cracked, bent, or missing teeth that would cause incorrect signal generation.
7. Clear the code and complete a full drive cycle that reproduces the conditions recorded in the freeze frame data — specific load, speed, and temperature conditions. If P0571 does not return, the issue may have been a temporary electrical glitch. If it returns, you have confirmed an ongoing fault that requires repair.

How to fix P0571

Always start with the least expensive and most frequently encountered causes before moving to more complex and costly repairs. Wiring problems and wheel speed sensors account for the majority of P0571 cases, while ABS module replacement is typically a last resort.

• Wheel speed sensor replacement — $120–$350. This is the single most common fix for P0571. Sensors can fail due to age, contamination, or physical damage from road debris.
• Sensor wiring repair — $80–$250. Broken wires, corroded connectors, or damaged grounds can often be repaired without replacing any components. Soldering and heat-shrink tubing restores a reliable connection at a fraction of the cost of new parts.
• ABS module repair or replacement — $400–$1,200. In cases where the module itself is faulty, repair via a specialist or full replacement is required. This is the most expensive scenario and should only be pursued after wiring and sensors have been ruled out.

How much does it cost to fix P0571?

The total repair cost for P0571 varies widely depending on which component is actually at fault. Based on typical parts and labor rates at independent repair shops in the United States, a wheel speed sensor replacement runs $120 to $350, wiring repairs typically cost $80 to $250, and an ABS module repair or replacement ranges from $400 to $1,200. In most cases, the overall cost falls somewhere between $80 and $1,200. Spending time on a thorough diagnosis before purchasing any parts is strongly recommended — the most expensive repair is almost never the first one to try, and ruling out simpler causes can save hundreds of dollars.

Can you drive with P0571?

P0571 carries a Caution severity level. Your standard friction brakes will continue to function normally, so you are not stranded. However, the ABS and electronic stability control systems are effectively disabled when this code is active. On dry pavement, stopping distances remain largely unchanged. On wet, icy, or loose gravel surfaces, the loss of these systems means significantly longer stopping distances and reduced ability to maintain directional control during hard braking. Driving with P0571 set is possible in the short term, but the vehicle should be diagnosed and repaired as soon as reasonably possible, and aggressive or high-speed driving should be avoided until the fault is resolved.

Related OBD2 codes

• P0500: Vehicle Speed Sensor "A" Malfunction
• P0501: Vehicle Speed Sensor "A" Range/Performance
• P0502: Vehicle Speed Sensor "A" Low Input
• P0503: Vehicle Speed Sensor "A" Intermittent/Erratic/High
• P0504: Brake Switch "A"/"B" Correlation
• P0505: Idle Control System Malfunction