Closeup of a spark plug.

3 Steps For How To Test A Lawn Mower Coil

4 minutes

A lawn mower’s ignition coil creates the spark that gets the lawn mower running. So, it’s important to test the coil from time to time. But, how to test a lawn mower coil?

What Do Lawn Mower Coils Do?

Lawn mower ignition coils help create a spark so that the engine can run. A flywheel is connected to an ignition coil and a magnet is mounted to the flywheel. When the lawn mower is turned on, the flywheel spins, and the magnet repeatedly passes by the ignition coil, creating an electric charge. Ultimately, with the help of the spark plug, this creates a spark that gets the engine going.

Why Do Lawn Mower Coils Go Bad?

Ignition coils are nothing more than a wire twisted around a core. They get twisted so many times they end up looking like springs.

Sometimes lawn mower coils can go bad due to poor manufacturing. They can also go bad due to battery or voltage regulation problems. There’s also the possibility that they go bad due to a wreck of some kind.

There are unfortunately lots of reasons why an ignition coil can go bad. Thankfully, testing this is simple.

3 Steps For How To Test A Lawn Mower Coil

Closeup of a multimeter, which can be used to test a lawn mower coil.
Multimeters have a lot of uses.

Testing a lawn mower coil is not that complicated. You can do it very easily if you just follow some basic steps while using a multimeter.

1. Set Up The Multimeter

The first thing to do is to confirm the multimeter is in ohm mode. Then, set the multimeter to the 20 kilos (20 K) range.

After that, insert 2 wires into the multimeter. Put the red one in the common point and the black one in the Ohm signed port. Then check whether the meter is performing properly. It should give 0 and 1 readings respectively while touching both ends of the wire and disconnecting them.

2. Expose The Ignition Coil

To test the coil, you’ll need to access it. If you feel a little unsure about doing this, checking your owner’s manual can help with instructions and pictures. Otherwise, start by removing the engine cover.

Next, remove the coil cover. If you’re not sure where the coil is, you just need to look for the metal box the spark plug wire is attached to. This box is the coil cover.

Before testing the ignition coil, disconnect all connected wires except the spark plug wire. You can take off the other end of the spark plug wire though. Keep it away from the spark plug.

3. Connect The Multimeter And Test The Coil

Take the red lead of the multimeter and put it into the spark plug’s boot. You’ll want to put it far enough in so that it touches the metal plate in the boot.

Next, put the black lead against the coil and watch what happens on the multimeter. If the multimeter is reading between 2.5 and 5 K ohms, then you’re good. If it shows something else, a 1 or infinity sign, for example, then the coil needs to be replaced.

3 Steps For How To Replace Lawn Mower Coil

Man doing some maintenance on a lawn mower.
Lawn mower maintenance is an important part of mowing a lawn.

So, you’ve just discovered that your lawn mower coil is bad and needs to be replaced. The good news is this is a really easy process.

Let’s get to it.

1. Buy The Right Lawn Mower Coil

Every lawn mower is a little different. This means ignition coils can be different too. If you have your owner’s manual, use that for a reference to purchase your ignition coil. If not, it might take some research, but it’s worth doing so you don’t get the wrong model.

2. Get Access To The Old Lawn Mower’s Coil

Doing this simply requires the same process as before. Remove the engine cover and then the coil cover. Next, disconnect all the wires connected to the coil except the spark plug wire.

Once that’s done, use a screwdriver to remove the screws holding the coil in place. Then take it out.

3. Put In The New Lawn Mower Coil

Put the new coil into the coil box just like the old coil was. Screw the screws back in and reconnect all the wires. Test the new coil with your multimeter and you’re good to go.

In Conclusion: How To Test A Lawn Mower Coil

Sometimes a process can seem more complicated than it is. Thankfully, when it comes to how to test a lawn mower coil, it’s incredibly simple.

So, what do you think? What maintenance tricks have you learned over the years? We’d love to hear your thoughts below!

Todd L Miles
Lawn Mowers Enthusiast
I started "Landscape and Lawns Care" to provide clients with lawn care with better service, better products and, most importantly, better ethics. My promise to every customer is to give the greenest grass possible while controlling weeds, insects, and diseases! The most important thing is that I strive to always do the right thing for you, your lawn and your wallet!