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Car Starts Then Dies

An engine that fires and stops within a few seconds is often stopped by the immobiliser, or it has an idle control, air leak or fuel pressure problem.

Normal risk

Not dangerous by itself, but find the cause before relying on the car.

Short answer · Why does my car start and then cut out?

If it always dies after one or two seconds, the immobiliser is the prime suspect: it lets the engine fire and then cuts fuel when the key is not recognised. If it runs a little longer and stalls at idle, think of idle control, a large vacuum leak, a mass air flow sensor fault or low fuel pressure.

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Safe checks you can do

  1. Watch the security lightFlashing after the engine dies points to the immobiliser.
  2. Try the spare keyIf the car keeps running, the first key is the problem.
  3. Hold the revs slightlyIf it keeps running with a little throttle, idle control or air leaks are likely.

Questions that narrow it down

  1. Does it always die after the same time?Immobiliser.
  2. Does it run with some throttle?Idle air or vacuum leak.
  3. Did it start after battery work?Idle relearn may be needed.

Possible causes

Listed without ranking. Use the questions above to see which ones fit your car.

  1. Immobiliser cut-offKey not recognised.
  2. Idle control faultDirty throttle or lost adaptation.
  3. Large vacuum leakMixture too lean.
  4. Low fuel pressurePump or regulator.
  5. Mass air flow sensorWrong air reading.

Questions about Car Starts Then Dies

Can a weak key battery cause it?

Yes on many keyless systems; replace the battery or hold the key near the start button.

Does disconnecting the battery help?

Rarely; it can even erase idle adaptations.