P0703 Brake pedal switch: circuit fault ("B")

By: Diagno editorial team · Updated: 2026-10-15

P0703 means: Brake pedal switch: circuit fault ("B"). The brake pedal switch tells the computer when the brake is pressed. Drive gently and have the car checked soon. The most common repair costs about €45–90 in Estonia, depending on make and model. The most common cause: connector loose, damp or corroded.

What it means

The brake pedal switch tells the computer when the brake is pressed. A wrong signal can affect the brake lights, cruise control and the gear selector lock. The computer found a fault in the electrical circuit: the part, a wire, a connector or a fuse.

What you may notice

• Brake lights don't work or stay on
• Cruise control doesn't work
• Automatic selector won't come out of P

What could be wrong

1. 1Connector loose, damp or corroded · Wiring or connector repair €45–90
2. 2Wire broken or chafed · Wiring or connector repair €45–90
3. 3Faulty brake light switch · Switch replacement €50–100
4. 4Engine computer fault (rare) · Control unit check and software €150–300

Repair difficulty: Easy

What you can check yourself

First look at the connector and wiring: anything loose, melted or green with corrosion? Have someone check that the brake lights come on when you press the pedal. Don't drive without brake lights. You can do the simpler checks yourself.

How we fix it

1. We read the fault data on the diagnostic tool and check whether the fault is constant
2. We measure the circuit's supply, ground and signal
3. We repair the wire or replace the connector
4. If the wiring is fine, we replace the brake light switch

Standard SAE description: Torque Converter/Brake Switch B Circuit Malfunction