What it means
The vacuum pump control circuit B is above the expected electrical threshold. This indicates a high circuit condition; the code alone does not identify its cause.
At a glance
- Usually lights the check-engine light
How it works
This code concerns the electrical control circuit for vacuum pump B, which supplies vacuum that may assist braking or serve other vehicle systems. The module detects that the circuit voltage is higher than expected; that can result from a wire shorted to battery voltage or an open pump winding that disrupts the circuit.
Common causes
Most likely first.
- Control wire shorted to a B+ supply
- Open motor winding or worn brushes
Symptoms
- Brake pedal may feel harder than usual
- HVAC airflow or operation may be reduced
How to diagnose it
- Record freeze-frame data and check for related pump or brake-assist codes to see when the fault occurred and whether other circuit faults are present.
- With the vehicle safely parked, check whether the brake pedal feels unusually hard and whether HVAC operation has changed, since either may rely on vacuum assistance.
- Inspect vacuum pump B, its connector, and the harness for loose pins, corrosion, chafing, or a control wire touching a B+ supply.
- Check the pump's electrical connections and winding for an open circuit using the manufacturer's test procedure and specification.
- If the pump and wiring look sound, test the control circuit for an unintended connection to battery voltage and verify module commands before considering a module fault.
Common fixes
- Clean and secure corroded or loose vacuum pump B connector terminals.
- Repair damaged control wiring or insulation that is shorting to B+.
- Replace vacuum pump B if its motor winding is open or its brushes are worn.
- Repair a confirmed control-module circuit fault after verifying the pump and harness.
Can I keep driving?
If the brake pedal is hard or braking assistance seems reduced, avoid driving and arrange a safe inspection because stopping may require much more effort. If braking feels normal, limit driving and watch for worsening pedal effort or HVAC problems.
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.