What it means
The ECU monitors the vacuum supplied to the brake booster (either via a dedicated sensor or via intake manifold pressure). The level has dropped below the calibrated threshold; brake-pedal feel will be hard, and an electric vacuum pump may be commanded to restore vacuum.
At a glance
- Usually lights the check-engine light
How it works
The brake booster uses vacuum to reduce the force needed at the pedal, and the control module monitors that vacuum through a sensor or pressure data. P050F sets when booster vacuum falls below the required level, which can make the pedal unusually hard and increase the effort needed to stop.
Common causes
Most likely first.
- Vacuum leak in booster line or check valve
- Electric vacuum pump weak
Symptoms
- Brake warning light may illuminate
- Brake pedal feels unusually hard
- Stopping may require more pedal effort
- Possible hissing near the brake booster
How to diagnose it
- With the vehicle stationary, assess whether the brake pedal is unusually hard and note any brake warning indicators before moving it.
- Read freeze-frame data and available brake-vacuum or pressure live data to see when vacuum fell below the expected level.
- Inspect the booster vacuum hose, check valve, and connections for cracks, looseness, or a hissing leak.
- Check the booster for loss of vacuum retention and inspect the electric vacuum pump, if fitted, for operation and wiring condition.
- Test the vacuum supply and related sensor or pump circuit against the manufacturer's specification.
Common fixes
- Reconnect or replace a leaking booster vacuum hose.
- Replace a faulty vacuum check valve.
- Repair wiring or connections to an electric vacuum pump.
- Replace a weak vacuum pump or leaking brake booster after testing confirms the fault.
Can I keep driving?
Do not drive if the brake pedal is hard or stopping requires unusual effort; arrange safe recovery because braking assistance may be reduced. A vacuum leak can also affect engine running, and continued use may make stopping harder.
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.