Engine Starts Then Dies Immediately
The engine starts but stalls right away, indicating a fuel, air, or security system issue. This is a common symptom on 2020 Silverado 1500 models, often related to fuel pump failure, anti-theft system activation, or a vacuum leak.
Diagnosis Details
Possible Causes
Fuel pump failure or low fuel pressure – The pump may not maintain pressure after initial start, causing the engine to stall.
Anti-theft system (Passlock or immobilizer) – A security system fault can cut fuel or spark after starting.
Vacuum leak (intake or PCV) – Unmetered air causes a lean condition and stall at idle.
Faulty mass airflow (MAF) sensor or throttle body – Incorrect air/fuel mixture can cause immediate stalling.
Crankshaft position sensor failure – Loss of signal can kill the engine after start.
Related OBD-II Codes
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What You Should Do
Check fuel pressure with a gauge; should be 55-62 psi.
If low, replace fuel pump.
Scan for trouble codes, especially P1629 (anti-theft) or P0335 (crank sensor).
Inspect for vacuum leaks using smoke test.
Clean throttle body and MAF sensor if dirty.
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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.
