Engine Cranks But Won't Start When Warm
The engine cranks normally but fails to start when warm, indicating a fuel or ignition issue that is temperature-sensitive. Common causes include a failing crankshaft position sensor, fuel pump relay, or vapor lock.
Diagnosis Details
Possible Causes
Faulty crankshaft position sensor (CKP) – loses signal when hot, preventing spark/fuel injection.
Failing fuel pump or fuel pump relay – heat causes electrical resistance or relay failure.
Vapor lock in fuel system – fuel boils in lines when hot, blocking flow.
Related OBD-II Codes
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What You Should Do
Check for spark and fuel pressure when the engine is warm.
Test the crankshaft position sensor resistance and signal.
Inspect fuel pump relay and listen for pump prime.
Allow engine to cool and retest.
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.
