Converts the 12-volt battery current into 20,000-40,000 volts needed to create a spark at the spark plug, enabling combustion in each cylinder.
$150 – $400
Total Cost
As needed (typically 80,000 – 120,000 miles)
Replace Interval
Easy
DIY Difficulty
Fix Within a Week
If It Fails
Ignition coils transform your car's low-voltage battery power into the high-voltage spark needed to ignite fuel. Modern cars use one coil per cylinder (coil-on-plug design), so a single failure affects only one cylinder.
Parts Cost
$30 – $100 per coil
Labor Cost
$50 – $150
Replace immediately when diagnosed. A failing coil puts stress on the catalytic converter. If one coil fails at high mileage, budget for replacing all of them within 10,000 miles.
BMW ignition coils are a known weak point. They often fail around 60,000-80,000 miles. Replace all coils and plugs together.
VW/Audi 2.0T engines eat ignition coils. Keep a spare in the trunk. Genuine Bosch or Eldor coils are recommended over cheap aftermarket.
Ford EcoBoost engines generally have reliable coils, but moisture intrusion in the coil wells can cause misfires. Check for water in spark plug wells.