What a spark plug cross reference chart does

A spark plug cross reference chart is a table that matches spark plugs from different manufacturers to one another. If your engine calls for a Champion spark plug but you can only find a Bosch, or vice versa, the chart tells you which Bosch plug will work the same way. The chart exists because different companies use different part numbers for plugs that have identical heat ranges, gap sizes, and thread types — the three things that actually matter to your engine.

The chart does not tell you whether a spark plug is right for your specific vehicle. That is what your owner's manual or a parts store lookup does. The cross reference chart only translates between brands once you already know what you are looking for.

Key Takeaways

  • A cross reference chart matches spark plugs from different manufacturers so you can swap brands if your first choice is unavailable.
  • The chart works because spark plugs are defined by heat range, gap size, and thread type — not by brand name.
  • You must find your vehicle's correct spark plug specification first, using your owner's manual or a parts store database, before using a cross reference chart.
  • Bosch, NGK, Denso, Champion, and Autolite are the five brands most commonly cross-referenced against each other.
  • A cross reference chart is a translation tool, not a replacement for checking your vehicle's requirements.

Where to find a cross reference chart

The most reliable cross reference charts are published by the spark plug manufacturers themselves. Bosch, NGK, Denso, Champion, and Autolite all post searchable cross reference tools on their websites. You enter the part number you have (or the one your manual specifies), and the tool shows you the equivalent from other brands.

Parts retailers like AutoZone, O'Reilly Auto Parts, and NAPA also host cross reference charts on their websites. These are usually free to use and do not require you to create an account. Some retailers let you search by vehicle year, make, and model instead of part number, which can be faster if you do not have the manual handy.

Print cross reference charts exist in older spark plug catalogs and some automotive repair manuals, but they go out of date as manufacturers discontinue old part numbers. Online tools are updated more frequently and are easier to search.

How to use a cross reference chart correctly

Start by finding your vehicle's correct spark plug specification. Open your owner's manual and look for the maintenance section or specifications page. It will list the spark plug brand and part number — for example, "NGK BPR6ES" or "Champion RC12YC." Write this down exactly as it appears.

Go to the cross reference tool you chose and enter that part number into the search box. The tool will return a list of equivalent plugs from other manufacturers. Each equivalent plug will have the same heat range (the number in the middle of the part number, usually), the same gap size (the distance between the electrodes), and the same thread size (how it screws into the engine). Any of these plugs will work in your engine.

Do not use the cross reference chart to look up a plug by vehicle year and model alone. Different trim levels, engine sizes, and model years of the same vehicle often use different spark plugs. Always start with your owner's manual or a parts store lookup that asks for your specific vehicle details.

Why heat range matters when cross referencing

Heat range is a number embedded in the spark plug part number that tells you how hot the plug runs. A "hot" plug (lower number) stays hotter and is used in engines that run cool. A "cold" plug (higher number) runs cooler and is used in engines that run hot. Using the wrong heat range can cause fouling (carbon buildup that stops the plug from firing) or pre-ignition (the fuel igniting too early and damaging the engine).

When you cross reference a spark plug, the heat range must stay the same. If your manual calls for an NGK BPR6ES, the "6" is the heat range. Any equivalent plug from another brand must also have a heat range of 6. A cross reference chart will only show you plugs with matching heat ranges, so you do not have to calculate this yourself — but it is worth understanding why the number matters.

Gap size and thread type in a cross reference

The gap is the space between the center electrode and the ground electrode where the spark jumps. Most modern spark plugs come pre-gapped from the factory, but some older plugs or specialty plugs require you to set the gap yourself using a gap tool. When you cross reference a plug, the gap size should match — usually between 0.028 and 0.044 inches, depending on your engine.

Thread size is how the plug screws into the cylinder head. Most passenger vehicles use a 14 mm thread, but some use 10 mm or 12 mm. Truck engines and older vehicles may use different sizes. A cross reference chart will only show you plugs with the same thread size, so you will not accidentally order a plug that does not fit.

When a cross reference chart cannot help you

If your owner's manual specifies a spark plug that has been discontinued, a cross reference chart may not have an entry for it. In this case, contact the manufacturer directly or visit a parts store with your vehicle's year, make, and model. The parts store can tell you what modern equivalent is closest to the discontinued plug.

Some specialty spark plugs — like iridium or platinum plugs — may not cross reference to standard copper plugs, even if the heat range and gap are the same. These plugs have different electrode materials and last longer, but they are not interchangeable with standard plugs in all cases. Check the manufacturer's cross reference tool or ask a parts store before substituting.

If you are working on a vehicle older than the 1970s or a specialty engine (motorcycle, small engine, marine), a standard cross reference chart may not cover it. Older spark plugs used different numbering systems, and specialty engines have unique requirements. A mechanic familiar with that vehicle type is your best resource.

Frequently Asked Questions

Can I use any spark plug as long as the heat range matches?

No. Heat range, gap size, and thread type must all match. A cross reference chart ensures all three do, so you should only use plugs the chart shows as equivalent. Using a plug with the wrong gap or thread size can damage your engine or cause it to misfire.

Do I need to gap a spark plug after I cross reference it?

Most modern spark plugs come pre-gapped and do not need adjustment. Check the package or the manufacturer's instructions. If the plug is pre-gapped and matches your specification, do not adjust it. Changing the gap on a pre-gapped plug can damage the electrodes.

What if the cross reference chart shows multiple plugs from the same brand?

Different part numbers from the same brand usually indicate different heat ranges or gap sizes. Make sure you pick the one that matches your original specification exactly. If you are unsure, a parts store can confirm which one is correct for your vehicle.

Can I cross reference a spark plug I found online to make sure it is the right one?

Yes. Enter the part number into a cross reference tool to see what it is equivalent to, then compare that to your owner's manual specification. If the cross reference shows your manual's plug as an equivalent, the online plug is correct. If it does not appear, the online plug is not a match.

Are iridium spark plugs cross referenceable to standard plugs?

Sometimes, but not always. Iridium and platinum plugs may have different part numbers even when the heat range and gap match a standard plug. Check the manufacturer's cross reference tool specifically, or ask a parts store. Do not assume a standard plug and an iridium plug are interchangeable just because the numbers look similar.