What it means
The control module monitors the vacuum sensor’s supply voltage. It sets this code when that voltage falls below the expected range.
How it works
The control module supplies power to the vacuum sensor, which reports vacuum used to assess brake assist. This code sets when the supply voltage is below the expected range, often because the supply wire is shorted to ground or a connection is faulty.
Common causes
Most likely first.
- Short to ground in the supply wire
- Damaged or corroded connector
- Faulty vacuum sensor
- Control module fault
Symptoms
- Brake or stability-control warning light on
- Brake assist may be affected
How to diagnose it
- Scan the brake or stability module and review freeze-frame and live data for the vacuum sensor supply fault.
- Inspect the sensor connector and supply harness for corrosion, water, damaged insulation, or a wire contacting ground.
- Check the connector terminals for looseness and verify that the sensor supply circuit is not shorted to ground, following the vehicle wiring information.
- Test the supply circuit and connector voltage against the manufacturer's specification with the sensor connected and disconnected as directed by the service procedure.
- If the wiring and supply are correct, test the vacuum sensor and then the control module according to the manufacturer's procedure.
Common fixes
- Repair supply wiring that is chafed or shorted to ground.
- Clean or repair a corroded or loose sensor connector.
- Replace a faulty vacuum sensor after confirming the supply circuit is sound.
- Repair or replace the control module only if its output fails the specified tests.
Can I keep driving?
Brake assist may be reduced, which can increase pedal effort and stopping distance. Avoid high-speed or heavy-traffic driving if braking feels different, and get the fault checked promptly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.