A Ford Mechanic's Guide to Spark Plugs for the 2005-2007 Ford Five Hundred

Signs of Failing Spark Plugs

When spark plugs wear out, they can't create a strong spark every time. This is called a misfire. You will notice problems with how your car runs. These signs usually start small and get worse over time.

• Rough Idle: Your car might shake or sputter when you're stopped at a light. This is often the first sign you'll notice.
• Poor Acceleration: The car may feel sluggish or slow to respond when you press the gas pedal.
• Check Engine Light: A misfire will almost always turn on the check engine light. If the light is flashing, it's a severe misfire that can damage other expensive parts like the catalytic converter. Stop driving if you see a flashing check engine light.
• Worse Gas Mileage: When fuel isn't burned properly, your car uses more of it. You'll find yourself filling up the tank more often.
• Hard Starting: The engine may take longer to crank and start, especially when it's cold.

A Word of Warning on This Repair

Changing the spark plugs on the 2005-2007 Ford Five Hundred is not a simple job. The 3.0L V6 engine is mounted sideways in the engine bay. This means three of the spark plugs are at the front and are easy to get to. However, the other three are at the back, tucked under a large plastic part called the upper intake manifold. To get to the rear spark plugs, this entire manifold must be removed. 🎬 Watch this step-by-step guide on removing the intake manifold and plugs. This turns a simple tune-up into a much more involved repair that requires disconnecting fuel lines, electrical connectors, and various hoses. Because of this difficulty, many owners choose to replace the ignition coils and intake manifold gaskets at the same time. 🎬 See how to replace the ignition coils while you are there. This is a good idea, as you don't want to do the job twice.

Choosing the Right Aftermarket Spark Plugs

The original plugs in your Five Hundred were likely platinum plugs designed to last about 100,000 miles. When choosing a replacement, you have several options. You don't need to buy the most expensive plug, but sticking with a quality brand is a smart move, especially given the labor involved in changing them.

Brand Quality Tiers

• Top Tier (Recommended): NGK and Denso are world-class brands known for excellent quality and reliability. They are often original equipment for many carmakers. Using their Iridium or Double Platinum plugs is a great choice for longevity and performance.
• OEM & Quality Equivalents: Autolite and Motorcraft are the original brands for Ford. You can't go wrong with these. Bosch and Champion are also long-standing, reputable brands that offer quality platinum and iridium options that will perform well in your Five Hundred.
• Economy Tier: Skyward is a budget-friendly option. While they will work, they may not have the same lifespan or quality control as the top-tier brands. Given the difficulty of this specific repair, saving a few dollars on the plugs themselves may not be worth the risk of having to do the job again sooner.

Spark Plug Material: What's the Difference?

• Copper: Basic, good performance, but wears out the fastest (every 20,000-30,000 miles). Not recommended for this car due to the difficult installation.
• Platinum/Double Platinum: A big step up in lifespan (60,000-100,000 miles). The original plugs were platinum. Double platinum is better for engines like this one.
• Iridium: The best material for longevity and a strong spark (often 100,000+ miles). They cost more but are worth it for a hard-to-reach job.

Cost to Replace Ford Five Hundred Spark Plugs

Note: Costs are estimates. Prices for parts and labor can vary by location and the specific parts chosen. The high labor cost is due to the need to remove the intake manifold to access the rear three spark plugs.

Frequently Asked Questions