What is the ignition coil?
An automotive ignition coil is a transformer that receives the low voltage of the battery and produces thousands of volts. This very high amount of voltage is necessary to jump the gap on the spark plug to produce the spark needed for combustion. On older engines, ignition coils were either built in to the distributor, or fixed nearby and feed spark to the distributor. In modern engines, computers (modules) have replaced distributors and command the ignition coils to fire. Computer control of spark timing allows for very precise firing of the plug in relation to piston and valve movement – improved fuel economy, emissions and power. Coils can either fit onto each spark plug or be placed together in a pack with cables to each plug.
What are the symptoms of a worn or faulty ignition coil?
No spark means either a misfiring engine, or in the case of one large coil, one that does not run. Ignition coils typically fail from age. The plastic housing becomes brittle with heat, and the metal core becomes fatigued from high voltage. Spark will bleed through the housing or fail to reach the spark plug. Either way the coil needs to be changed. Although coils may be considered a “tune-up” part, most manufacturers do not publish a service table for coils.
How soon should I replace a faulty ignition coil?
As soon as possible. This type of failure will most likely leave you stranded on the side of the road. Even if the car still runs, misfiring may damage other parts of the engine, particularly the catalytic converter. Your best bet is to find a reputable mechanic and set an appointment as soon as possible. Most coil replacement can be done same day, but times do vary between makes and models, so plan on dropping off the car. Think about the last spark plug replacement or “tune-up” done to the car. Changing plugs at the same time as coils may save you some time and money.
What is the typical cost for Ignition Coil Replacement?
- Estimated part(s) cost $60–$80
- Estimated labor cost $50–$90
Prices for coil replacement will vary greatly with make and model. On older engines, the coil that feeds the distributor may only cost about $60 to $80 for the part and another $40 for the installation. However, some coils are built into the distributor, so the whole unit must be replaced usually pricing out around $300 to $400 dollars and another $90 for the installation. On more modern cars, individual coils that feed one spark plug may only cost around $60 to $80 with installation ranging from $20 to $300 depending upon the location.
A coil that is on the top part of the motor or on the side facing the radiator might be very simple to replace. On the other hand, a coil on the side of the motor near the firewall where other parts of the motor need to be removed will be more difficult and cost more in labor. Coils that are grouped together as a pack will be more expensive, reaching into the $150 to $300 range depending upon the size of the motor and how the coils are grouped. Labor for these packs are usually in the $50 to $90 range.
Most automotive service professionals can perform this service, however the pricing will vary significantly based on vehicle type and location. Use Openbay to compare and book this service from local auto-repair shops.
This article was written by an ASE Master Technician.