Hard Brake Pedal Diagnosis
A consistently hard brake pedal indicates a loss of power brake assist, often due to a vacuum leak, failed brake booster, or faulty check valve. This significantly increases stopping distance and effort.
Diagnosis Details
Possible Causes
Vacuum leak in the brake booster or its hose
Failed brake booster diaphragm or internal seal
Faulty check valve on the booster vacuum line
Clogged or restricted vacuum source (e.g., intake manifold port)
Related OBD-II Codes
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What You Should Do
Inspect the vacuum hose from the intake manifold to the brake booster for cracks, disconnection, or collapse.
Check the check valve (should hold vacuum one way).
If no leak is found, test the brake booster by pumping the brake pedal with engine off, then start the engine; pedal should drop slightly.
If not, replace the booster.
Also verify engine vacuum is adequate (typically 18-22 inHg at idle).
Related Repairs
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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.
