The gearbox or cruise system is not seeing a reliable brake pedal signal. Symptoms include cruise control not engaging, the car refusing to shift out of park, and brake lights behaving oddly.
P0703 — also written PO7O3, P 0703, 0703 — is the OBD-II code for brake switch 'b' circuit malfunction. Same code, same fix: this page covers every spelling of it.
P0703 is a transmission fault code, typically costing £50–£180 to put right in a UK garage.
What causes P0703?
- Failed brake light switch (cheap and very common)
- Misadjusted switch after pedal work
- Blown brake light bulb affecting the circuit
- Wiring fault at the pedal box
How P0703 is fixed
- Replace and correctly adjust the brake light switch
- Replace failed bulbs
- Check the pedal box loom
P0703 repair cost in the UK
Most P0703 repairs land between £50–£180 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Can you drive with P0703?
Yes, but check your brake lights are working before you drive.
Urgency: medium.