Maintaining your vehicle is an incredibly rewarding task and learning how to replace your spark plugs is a great place to start. There’s a good chance you will need to replace your old spark plugs several times while you own a a 2003 Ford Focus. Spark plugs are one of the most vital parts inside your engine as they start the entire combustion process that starts and keeps your engine running for many thousands of miles. Similar to most engine parts, spark plugs experience wear over time and eventually need replacement, but fortunately this is a repair you can do yourself. Chances are, if you’ve found yourself here, you have no idea how to do that, or perhaps you’d just like to know what kind of spark plugs you need to buy. The entire process of changing your spark plugs should take roughly 20-45 minutes. This article will go over everything you should need to know about your Ford Focus’s spark plugs, whether you need some general information or a full, step-by-step guide to performing a spark plug change.
Correct spark plugs on a 2003 Ford Focus
How often should I change my spark plugs?
Generally, it is advised that you replace spark plugs once every 20,000 to 40,000 miles. Of course, please make sure to check your owner’s manual to determine the specific interval determined by Ford for the 2003 Focus. Of course, if you drive your vehicle more aggressively or own a Focus with some modifications, you may want to consider changing your spark plugs closer to the 20,000 miles end of that spectrum.
However, there are also telltale signs of a car that may need a spark plug replacement prematurely, such as:
- Engine misfiring
- Rough idle
- Problems starting your engine
Note that this list is of course not comprehensive, and these problems on their own do not necessarily point to the spark plugs being the standalone culprit. However, the best way to prevent any issues with your vehicle is to take care of it with regular maintenance, and you are definitely doing so with the responsible decision to replace your Ford Focus’s spark plugs on a regular basis.
Changing spark plugs on a 2003 Ford Focus
This is a process you can do on your own with some standard garage tools. Of course, consult your owner’s manual, as well as a factory service manual (FSM) or an equivalent Haynes or Chiltons manual. The video shown below does a good job of outlining the process.
Helpful Tools
- A set of spark plug sockets – These come in very handy because many standard sockets are not deep enough for spark plugs. Additionally, some spark plug holes are a bit smaller, so it requires a thinner wall like the one featured in the product here to fit. The linked product also features a magnet to keep a good hold of the spark plug so you do not drop it into your engine bay!
- A spark plug tester – this is definitely a niche tool, but it can save you a ton of time. Although we’ve discussed spark plug replacement being a good thing to replace regularly and not just when issues occur, you may also be replacing your spark plugs because of an issue. This tool can help you diagnose the definite problem.
- A torque wrench is a very important tool to have in your collection. You should check your factory service manual to determine the correct torque rating to use when putting in the new spark plugs for your 2003 Ford Focus to be sure they are installed properly.
- A spark plug gap tool. This allows you to check the gap of your spark plugs and increase or decrease it if necessary. Most plugs will come pregapped, but if this is not the case, you should absolutely have one of these.
- I also highly recommend you have a feeler gauge as it makes it a bit easier to check the exact gap, and it is helpful for a decent number of other jobs.
Tips for changing spark plugs on your 2003 Ford Focus
- The most important thing is to avoid overtightening the plugs or worse, cracking them due to overtightenting. Use a torque wrench capable of lower, more precise torque ratings to be sure that you don’t make this mistake.
- You should replace spark plugs on a cold engine. Ensure you wait at least 30 minutes after your engine has been running before attempting to replace the spark plugs on your 2003 Ford Focus
- It’s not a bad idea to use dielectric grease when installing new spark plugs. You can apply a a tiny amount to the inside of the boot and the ceramic part of your spark plugs. It lessens the chance of voltage leak and helps avoid the misfortune of the boot fusing to the spark plug over time.
- Take this (unofficial advice) lightly as many spark plug manufacturers advise against the use of anti-seize. However, I have heard from numerous old-school mechanics that they always apply a light coating of anti-seize to the threads of their spark plugs, especially on older vehicles.
- Before beginning, remove the negative terminal of your battery. It is wise to disconnect the battery anytime you work on the electrical system of your Ford Focus or any other vehicle.