Engine Cranks But Won't Start When Cold
The engine cranks normally but fails to start when cold. This indicates a lack of either fuel, spark, or compression, or a sensor issue affecting cold-start enrichment. Common causes include a failing fuel pump, faulty crankshaft position sensor, or coolant temperature sensor malfunction.
Diagnosis Details
Possible Causes
Fuel pump not holding pressure or weak when cold
Crankshaft position sensor failing intermittently when cold
Engine coolant temperature sensor sending incorrect signal (too warm) to PCM
Faulty ignition coil or spark plugs (worn or fouled)
Fuel injector leak or clog (causing loss of prime)
Related OBD-II Codes
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What You Should Do
Check fuel pressure at the rail (should hold pressure after key off).
Scan for diagnostic trouble codes (DTCs) with a professional scanner.
Test crankshaft position sensor signal and coolant temperature sensor resistance when cold.
Inspect spark plugs and coils for wear or moisture.
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.
