Working Principles, Functions and Installation of Ignition Coil in Toyota Camry

An ignition coil is an essential component in an engine’s spark plug system that converts battery voltage into thousands of volts to produce spark plugs that ignite fuel efficiently. It resembles a simple wire-wound transformer filled with insulators.

Failure of one or more ignition coils in your Toyota Camry could result in misfires and reduced fuel economy, but these ignition coils can usually be repaired or replaced quickly and affordably.


An ignition coil’s primary purpose in your vehicle is to convert on-board battery voltage, usually 12 volts, into high voltage current capable of crossing over between spark plug electrodes and lighting fuel ignition. It essentially serves as a wire-wound transformer filled with insulation material.

While in use, the magnetic field of primary windings generates voltage spikes that induce higher-voltage current in secondary windings. When interrupted by your vehicle’s computer or ignition system, this magnetic field collapses and induces high voltage flows in secondary coils resulting in an electric spark which ignites your air/fuel mixture and starts your engine.

Today’s Coil-on-Plug (COP) systems come in various physical and wiring configurations. Some may employ a single coil that feeds voltage into a distributor while others mount directly atop each spark plug for optimal results.

All ignition coils are subjected to extreme heat and vibration, leaving them susceptible to failure over time. Internal electrical components may break down or short out insulation or windings, causing its output voltage to exceed safe limits – often enough to damage spark plug wires delivering energy directly to spark plugs. You can test both primary and secondary windings of an ignition coil with a multimeter to ascertain their condition – consult your repair manual or online service information for details regarding touchpoints or resistance readings for each winding.


Ignition coils supply high-voltage energy used to fire spark plugs that ignite and burn fuel for engine combustion, providing ignition coil packs with enough spark energy for start/run capabilities on newer Toyota Camry engines. These ignition coils use battery power as fuel and convert it into the spark needed to start and run them efficiently.

Early cars used a single ignition coil within a distributor that was responsible for providing spark plugs with their appropriate charges at precisely the right moment. While this system worked initially, its timing could become out-of-whack over time causing misfires in one or more cylinders of an engine. Modern cars usually utilize a coil on plug set-up with individual ignition coils being located directly above each spark plug within an engine block.

A malfunction can manifest as intermittent misfires in damp weather or first thing in the morning, and may also lead to surging at high RPM or difficulty starting or stalling while driving. Furthermore, its failure may reduce gas mileage significantly or bring about an obvious reduction in performance and power.

If your ignition coil has failed, replacing all four is often an advantageous move. Doing this may reduce the chance of other ignition components failing shortly thereafter, including spark plugs themselves. To do so, remove plastic engine covers or air intake tubes before finding and dismounting either an individual coil pack or pack of coils in the engine bay and disconnecting from their mounting bracket or, in case of distributorless cars, taking them from inside the distributor cap before installing your replacement ignition coil and testing your vehicle to make sure proper function.


This device is an essential component that takes the relatively low battery voltage and converts it into one with thousands of volts – this voltage then travels through to the spark plug to ignite fuel/air mixture in the combustion chamber, starting your engine. When an ignition coil becomes defective, however, your engine could misfire, leading to poor gas mileage, decreased performance while driving and even an audible “sputtering sound when you accelerate.

Heat and vibration from an engine bay can put ignition coils at risk of becoming damaged and less capable of increasing voltage. Once broken down, this insulation could create shorts between primary and secondary windings of an ignition coil limiting its ability to deliver high voltage spark plugs.

Most modern automobiles use a coil pack containing one ignition coil per cylinder of their engine, mounted in a boxy coil pack on either the fender or firewall and equipped with short leads directly connected to spark plugs. Others feature single coils mounted directly over each spark plug eliminating wires altogether. Malfunctioning coils may prevent the ignition system from firing spark plugs properly leading to reduced gas mileage as well as check engine lights being illuminated; such an issue would necessitate replacing all ignition coils as soon as possible!


When the coil breaks down, you may experience misfire in one or more cylinders and error codes P0300 to P0312 can be read off the computer/ECM’s diagnostic display depending on which cylinder has an issue. These errors could also indicate problems with crankshaft position sensors, primary circuit wires, and/or coil connectors.

A problem with this device component  will often prevent your car from starting, as well as have an obvious impact on acceleration and fuel economy. You will find yourself taking more effort to reach speed quickly, resulting in poorer gas mileage overall.

If you recognize any of these symptoms, a quick way to identify a defective ignition coil is using an OBD code scanner and reading each cylinder’s error codes – for instance P0303 could indicate this is happening; simply swap out its ignition coil with one for another cylinder like 2 and restart your Camry for test drives until all misfire errors disappear; that would indicate successful repair of its ignition coil!