Cold Start Cranks But Won't Start
The engine cranks over but fails to start when cold. This typically indicates a lack of fuel, spark, or air/fuel mixture issues, often related to cold-start enrichment systems.
Diagnosis Details
Possible Causes
Faulty coolant temperature sensor (ECT) causing incorrect fuel mixture
Weak or failing fuel pump (low pressure, especially when cold)
Dirty or failing idle air control valve or throttle body
Faulty spark plugs or ignition coils (weak spark when cold)
Fuel injector leak or clog (affects cold start enrichment)
Engine coolant temperature sensor wiring issue or connector corrosion
Related OBD-II Codes
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What You Should Do
Check for diagnostic trouble codes (DTCs) first.
Test coolant temperature sensor resistance and compare to specifications.
Check fuel pressure at the rail during cranking.
Inspect spark plugs for fouling or wear.
Clean throttle body and idle air control valve if applicable.
Verify battery voltage and starter health.
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.
