P050F

Code

LAND ROVER P — Powertrain

Brake booster vacuum very low

Brand: LAND ROVER

Type: P — Powertrain

Views: UK: 11 EN: 31 RU: 18

AI status

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Page language: EN

Causes

Failed or weak vacuum pump (electric or engine-driven)
Leaking or disconnected vacuum hose(s) between pump/manifold and brake booster
Faulty one‑way (non‑return) check valve
Cracked or leaking vacuum reservoir (accumulator)
Internal brake booster diaphragm or housing leak
Faulty brake booster vacuum/pressure sensor or wiring/connector fault

Symptoms

Hard or heavy brake pedal requiring greater force to stop vehicle
Longer stopping distances and reduced brake assist
Brake warning light or stability/ABS warnings may illuminate
Audible hissing from under‑dash or engine bay near brake booster
Engine running issues if vacuum loss affects intake controls (rough idle)
Possible message on dash indicating low brake assist or service required

What to check

Retrieve and record all related DTCs and freeze frame data with a scan tool
Visually inspect vacuum hoses, clamps, fittings, reservoir and check valve for damage or disconnection
With key on/engine off, command electric vacuum pump (if fitted) and verify operation and relay/fuse presence
Measure vacuum at booster with a handheld vacuum gauge at idle and during pump operation
Smoke-test vacuum plumbing and intake for leaks
Monitor live PIDs: brake booster vacuum/pressure sensor, commanded pump state, pump current, MAP (intake manifold pressure) and engine RPM

Signal parameters

Expected static vacuum at booster (typical): ~18–22 inHg (~60–75 kPa) vacuum at idle or when pump has charged reservoir
Code may set when vacuum drops below roughly 12 inHg (~40 kPa) or other manufacturer threshold
Vacuum sensor output (if present): typically an analog voltage proportional to vacuum (example range ~0.5–4.5 V) — compare to manufacturer data
Electric vacuum pump current draw (typical range varies by vehicle): often in the single‑digit to low double‑digit amps (e.g., ~5–15 A); sudden open or shorted circuit values are abnormal

Diagnostic algorithm

Read and document all stored and pending DTCs and freeze frame. Clear codes and attempt to re‑create fault with a road test or commanded pump cycle.
Perform a visual inspection of vacuum hoses, check valve, reservoir and booster connections. Replace or repair any damaged components.
With a vacuum gauge attached to the booster port, measure vacuum at key on/engine off while commanding the electric pump (if fitted) and then with engine running. Record values at idle and under load.
If vacuum is not produced when pump is commanded, verify fuse, relay, power and ground to the pump. Backprobe pump connector to confirm voltage and check pump current draw.
If pump runs but vacuum is low, isolate and smoke‑test the vacuum system (hoses, reservoir, check valve, booster) to locate leaks.
Inspect and test the non‑return/check valve for correct function; replace if it allows reverse flow or leaks.
If plumbing and pump are good but vacuum still low at booster port, bench‑test or replace brake booster (internal diaphragm leak possible).
If a vacuum/pressure sensor is present, verify sensor signal with a multimeter/scan tool and replace if out of specification.
After repairs, clear codes and perform a road test and live data verification to ensure vacuum values remain within spec and DTC does not return.

Likely causes

Electric vacuum pump failure or no power to pump (common on diesels/turbocharged petrol)
Ruptured vacuum hose or loose clamp at the booster or pump
Stuck or failed non‑return check valve allowing loss of stored vacuum
Cracked vacuum reservoir or leaking connector
Internal failure of brake booster / diaphragm

Fault status

⚠️ Status

Brake booster vacuum very low — reduced brake assist. Service required to restore vacuum supply to brake booster.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

Repair manuals

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P050F — Brake booster vacuum very low