Engine Starts Then Dies When Cold
The engine starts but immediately stalls when cold, indicating a fuel, air, or sensor issue that prevents the engine from maintaining idle after startup.
Diagnosis Details
Possible Causes
Faulty engine coolant temperature sensor (ECT) sending incorrect signal to ECU, causing overly lean or rich mixture
Dirty or failing idle air control valve or throttle body causing insufficient air at idle
Weak fuel pump or clogged fuel filter not delivering enough fuel pressure during cold start
Vacuum leak (intake manifold gasket, PCV hose) leaning out the mixture when cold
Faulty mass airflow sensor (MAF) or intake air temperature sensor
Related OBD-II Codes
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What You Should Do
Check for diagnostic trouble codes first.
Inspect engine coolant temperature sensor and its wiring.
Clean throttle body and idle air control valve.
Test fuel pressure and check for vacuum leaks.
If no codes, monitor live data for ECT and MAF readings during cold start.
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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.
