Hard Brake Pedal Diagnosis - 2020 Ford Mustang
A consistently hard brake pedal indicates a loss of power brake assist, likely due to a failed vacuum booster, vacuum leak, or faulty brake booster check valve. This condition significantly increases stopping distance and effort, posing a safety risk.
Diagnosis Details
Possible Causes
Failed brake booster (vacuum leak inside booster diaphragm)
Brake booster vacuum hose or check valve leak/crack
Vacuum pump failure (if equipped) or engine vacuum issue (low intake vacuum)
Related OBD-II Codes
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What You Should Do
Do not drive the vehicle until repaired.
Inspect the vacuum hose from intake manifold to brake booster for cracks or disconnection.
Check the one-way check valve at the booster (should hold vacuum).
If no external leaks, replace the brake booster assembly.
Verify engine vacuum is within spec (typically 18-22 inHg at idle).
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Disclaimer: This AI-generated diagnosis is for informational reference only. Always consult a qualified mechanic for an in-person inspection. AutOwner is not responsible for decisions made based on this information.
