Engine backfires are one of the most obvious signs of car trouble, and they are annoying and potentially damaging to the vehicle’s exhaust and catalytic mechanisms.

Backfires happens for various reasons, and may be accompanied by a Check Engine light.

Common reasons why this happen:

When moisture or resistance in the vehicle’s electronic ignition system allows a crossover generation of current to the wrong cylinder.
A lean mixture produced by either an engine vacuum leak or low fuel-pump pressure.
A faulty air injection check valve (part of the vehicle’s emission control system) lets too much air into the vehicle’s exhaust system.
A failed air intake boot can produce a backfire by altering the feedback voltage to the PCM.
Faulty ignition part or spark plugs may also cause backfires if the ignition timing drifts off or the plugs fire intermittently.
An exhaust leak such as broken welds or other small holes can take in cool air during deceleration and produce a popping or backfiring in the exhaust system.
How important is vehicle backfiring repairs?

Backfires produces sudden high-pressure events in the exhaust system, and can do serious damage if left unrepaired. Have the car checked by a professional mechanic as soon as possible.
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