P0703 code meaning
Brake Switch B Circuit
Powertrain system Generic code P07xx codes Check engine light
What P0703 means
Brake switch A is usually the brake light switch, B a second, redundant contact or signal used to cancel cruise control, release the converter clutch, check 'brake before throttle' and for stop-start. Since about 2014 GM receives it as a CAN message from the body module and checks its integrity (rolling counter, protection value: 3 of 10 faulty in 2014, 9 of 17 in 2025) without the check engine light; cruise control is disabled. Subaru-based systems (Saab 9-2X) check the circuit electrically during stops and starts and light the MIL after two trips. An NHTSA investigation of Hyundai and Kia brake light switches lists P0703 with a brake light that stays on. Brake switch A codes are P0571–P0573, disagreement between A and B is P0504.
P0703 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1 hours
- Clears after repairAfter a drive cycle
Symptoms of P0703
- Cruise control cannot be engaged or drops out
- Brake light stays on or does not work
- Selector cannot be moved out of P (shift lock)
- Check engine light depending on the maker
Common causes of P0703
- Most likelyBrake light or double switch worn, corroded or misadjusted
- PossibleWiring or connector at the pedal damaged, fuse blown
- PossibleCAN message from the body module disturbed (GM: software, bus fault)
- Less likelyAftermarket LED lamps or trailer module distorting the circuit
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Brake switchBrake switch wiringBody control module
What each part of P0703 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 7 | Area: transmission. |
| 03 | The exact fault in that area. |
What to do next
- Note P0703 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0703
What does P0703 mean?
P0703 means "Brake Switch B Circuit". Brake switch A is usually the brake light switch, B a second, redundant contact or signal used to cancel cruise control, release the converter clutch, check 'brake before throttle' and for stop-start. It is a generic code, so it means the same on every make.
Is it safe to drive with P0703?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0703 fail an emissions test?
P0703 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P0703 to fix?
Difficulty: easy. A typical repair takes 0.3 to 1 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0703 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.