What Cause a bad ignition coil?How to longer ignition coil lifetime?

IGNITION COIL FAILURE REASONS

Average lifetime of ignition coil is around 100,000 miles or more.

It is not an easy worn out replacement car part but still could fail for variety of reasons.

#1. Coil insulation worn out due to aging.

#2. Coil's winding damaged with Heat & Vibration.

#3. Cheap quality ignition module overloads to cause coil circuitry damage during internal arcing.

#4. Moisture Intrusion

Difficult to imagine? Here are the reasons.

Ignition coil & spark plugs are mounted in the tube positioned in the valve cover. The seal between coil tube and valve cover can fail overtime, then caused oil leakage around coil & spark plugs. Be sure the gasket sit well and work properly can prevent coil failure reoccur.

Also, for some rare cases, A/C is built up above and water may drip directly onto coils. So some high-end coils may be applied one layer marine-grade grease to give better seal between terminal nuts.

#5. Spark Plug Gap

Malfunction coil could be caused with gaping spark plug and leaking valve cover. Carbon accumulation will lead to excessive gap spark plugs which should be replaced along with ignition coils to prevent further problems.

You'll be very surprised that how high possibility is the major reasons to cause ignition coil failure are #4 & #5.