Hard Brake Pedal Diagnosis - 2019 Nissan Altima
A consistently hard brake pedal indicates a loss of power brake assist. This is typically caused by a vacuum leak, failed brake booster, or faulty check valve. The condition significantly increases stopping distance and pedal effort, posing a safety risk.
Diagnosis Details
Possible Causes
Brake booster vacuum hose or check valve leak/disconnected
Failed brake booster diaphragm (internal leak)
Vacuum pump failure (if equipped) or engine vacuum issue
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 one-way check valve at the booster for proper operation (should hold vacuum one way).
If hose and valve are good, test the brake booster by pumping the pedal with engine off, then starting the engine—pedal should drop slightly.
If not, booster is likely faulty.
Also verify engine vacuum is adequate (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.
