The electrical spark that ignites the fuel in the combustion chamber originates from the Honda ignition coil. There are two ways of locating this ignition component. On older model Honda engines that have a distributor, the center wire on the distributor cap can be traced back to the ignition coil. On the new engines with electronic ignition, the ignition coil can be found by tracing back from the spark plug along its wire to the coil. Sometimes, it can be found right on top of the plug itself. This is made possible because the signal that fires each plug is now generated from the onboard computer instead of the distributor cap. Failure of the Honda ignition coil is rare, but does occur just like any other electrical component on your vehicle. It can also only be generating a weak electrical impulse that will reduce the efficiency of your Honda engine. In both instances replacement of the worn out part is warranted. If you are testing your ignition system the most practical way is to start with the spark plugs and their wires. If you find more than one with a weak or nonexistent spark, the ignition coil should then be investigated. First the output then the input with the output lead running to the distributor or the spark plugs. If there is still no electrical impulse then the input side has to be tested. On the older systems a minimum of 12 volts should be supplying the ignition coil. On the newer systems it varies but should also be close to 12 volts from the onboard computer. The most difficult part of replacing this ignition component is removing all of the other parts on the Honda engine so you can gain access to it.