Ford Focus P0300 Trouble Code – Test your Ignition Coil

The Ford Focus P0300 OBDII check engine code is a serious issue that’s usually caused by something related to your ignition system. Your ignition system is a DIS (Distributorless Ignition System) that uses several sensors and components to ignite the air fuel mixture properly. When these components are working in unison, your Ford Focus will run efficiently and idle perfectly. When one of these components fails, your Focus will idle poorly or exhibit hesitation and misfire.

If you have used an OBDII scan tool to retrieve your trouble code, and it returns as a Ford Focus P0300 check engine light it can be difficult to track down. Because the trouble code is not cylinder specific, it can be tough to trace down where the issue really lies. Today I’ll be showing you how to test your coil on plug ignition coils to see if any of them have gone bad, or there’s a wiring issue causing the misfire. In order to complete this DIY guide to your Ford Focus, you will need to use a digital multimeter. Today’s test vehicle is a 2013 Ford Focus with a 2.0 liter non-turbocharged engine in it.

Ford Focus P0300 Trouble Code – Test your Ignition Coil

To begin this guide you’ll be testing for power and ground at the coil on plug connector. Remember you are testing on the ENGINE harness side of the plug. This guide assumes you have already tested your spark plugs to make sure they are in good condition before continuing with this step.

Ford Focus P0300 Trouble Code – Test your Ignition Coil 11

Open your Ford Focus ST hood and you’ll see the engine and plastic engine cover. To remove the engine cover simply pull up and out on the cover to dislodge from your valve cover.

Ford Focus P0300 Trouble Code – Test your Ignition Coil 2

Now that you have your engine cover removed you can access the coil on plug ignition coils. These are connected by way of a three pin weatherproof connector. Using your digital multimeter you will be testing these for power and ground to make sure you have a proper signal at each coil.

Ford Focus P0300 Trouble Code – Test your Ignition Coil 4

The first circuit you will be testing for is the power signal on your ignition coil. This is PIN 1 on your ENGINE harness side of the ignition connector. Insert your Focus key and turn to the “ON” position and gently probe the front of this engine connector at PIN 1. There should be around 12 volts of power at this wire, and if you have this signal the next pin to check is the ground signal, which is PIN 2.

If you have power and ground at these circuits the next order of business is to check for the internal resistance of your ignition coil. Testing this can be done through Part 2 of our Ford Focus P0300 tutorial so please stay tuned. Have any questions about this testing guide? Leave us a comment below and let us know!




  1. Joel

    Good brand or website to buy OBDII Code redear?looking into buying a good code redear for OBDII. i have a Volkswagen, a Vag-com would be the best choice but its really expensive for me right. i am looking into buying a nice simple budget scanner but don’t know where to look exactly. i don’t really know much on scanners so any help would be greatly appreciated.I need obd2 my car is 2000. Obd1 is 95 and down. ILL deff. Check out pepboys. And if there are other places I csn check. A simple scan retrieve code, erase.thank you frankie. now ive been looking at the actrons but dont know which model number would be right.

    1. John Huh (Post author)

      Hi Joel, if you need something as simple as that, we would recommend a cheap wireless OBDII scan tool from here :

      The HH scanner is cheap, works great and connects to your smartphone. Thanks for commenting!

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