
Basic checks
Veepeak OBDCheck BLE
A Bluetooth LE adapter for reading standard engine codes and supported live data.
View on AmazonCruise Control/Brake Switch A Circuit Malfunction
The brake light switch signal seen by the ECU is implausible — for example, both contacts active simultaneously, or no signal change despite the brake pedal being pressed (cruise control engages and disengages on this signal). On many cars also disables shift interlock.
The brake light switch signal seen by the ECU is implausible — for example, both contacts active simultaneously, or no signal change despite the brake pedal being pressed (cruise control engages and disengages on this signal). On many cars also disables shift interlock.
One of the most commonly reported causes for this code — check this first.
Typical part cost: $20-170
A plausible cause — test and verify before replacing parts.
Typical part cost: $20-170
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Already have a compatible scanner? Use it. If not, a Bluetooth OBD2 adapter can help you confirm engine codes and check supported live sensor data before replacing parts.

Basic checks
A Bluetooth LE adapter for reading standard engine codes and supported live data.
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Regular diagnostics
A Bluetooth LE adapter with an automatic sleep feature for routine code and sensor checks.
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Another option
A Bluetooth LE adapter to consider when comparing supported vehicles and diagnostic apps.
View on AmazonIllustrations shown, not product photos. Check vehicle, phone and app compatibility before buying. These adapters do not guarantee access to ABS, airbags or manufacturer-specific systems. Clearing a code does not repair the fault and can reset emissions readiness monitors.
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P0571 means "Cruise Control/Brake Switch A Circuit Malfunction". It is a generic OBD-II code that points to a fault in the vehicle speed, idle control, auxiliary inputs.
brake switch failed (worn contacts, internal break); switch misadjusted (does not actuate at correct pedal position) — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical. Use the Wrenchify app for a full diagnosis specific to your vehicle.
Year, make, model + step-by-step repair help — free plan included.