2015 Ram ProMaster Spark Plug Replacement Guide

Quick reference

Why the right plug matters

Choosing the correct spark plug for your 2015 Ram ProMaster is crucial for optimal engine performance, fuel efficiency, and longevity. The "right" plug isn't just about fitment; it's about the heat range and electrode materials.

Heat Range

Spark plugs are designed with a specific "heat range" – a measure of their ability to dissipate heat from the combustion chamber. A plug that's too "hot" (dissipates heat slowly) can lead to pre-ignition and detonation, severely damaging your engine. A plug that's too "cold" (dissipates heat too quickly) can foul with carbon deposits, leading to misfires and poor performance. The OEM-specified plugs for your 3.6L Pentastar engine are precisely engineered for its operating temperatures.

Electrode Metal: Iridium vs. Platinum vs. Copper

• Iridium: This is what your 2015 ProMaster's 3.6L Pentastar engine comes with from the factory (NGK LIKMAR8H6). Iridium is extremely hard and has a very high melting point, allowing for fine-wire electrodes that produce a strong, focused spark. This design offers excellent durability and a long service life, typically 100,000 miles or more.
• Platinum: Platinum plugs are also durable and long-lasting, often rated for 60,000 to 80,000 miles. They are a step up from copper but generally don't offer the same extreme longevity or performance as iridium. You might find double-platinum plugs, which have platinum on both the center and ground electrodes for extended wear.
• Copper: Copper has excellent electrical conductivity but is a softer metal, making copper-core plugs less durable. They typically last only 20,000 to 30,000 miles. While cheaper, they are not suitable for your ProMaster's 3.6L Pentastar engine, which is designed for long-life iridium plugs with a much longer replacement interval.

Always stick with iridium plugs for your 2015 Ram ProMaster 3.6L Pentastar to maintain factory performance and service intervals.

How to gap a spark plug

While most iridium spark plugs come pre-gapped from the factory, it is always a good practice to double-check the gap before installation, especially if the plug has been dropped or mishandled. The 3.6L Pentastar engine requires a gap of 0.035 inches (0.9 mm).

To gap a spark plug:

1. Use the right tool: A wire-type spark plug gapping tool or a feeler gauge is ideal. Avoid using coin-style gappers on fine-wire iridium or platinum plugs, as they can damage the delicate electrode.
2. Check the gap: Carefully insert the correct size wire or blade between the center and ground electrodes. It should slide through with a slight drag.
3. Adjust (if necessary): If the gap is too small, gently pry the ground electrode open slightly using the gapping tool. If the gap is too large, carefully tap the ground electrode on a clean, hard surface to close it. Be extremely gentle to avoid damaging the iridium tip.
4. Re-check: Always re-check the gap after any adjustment.

Replacement procedure tips

Replacing spark plugs on your 2015 Ram ProMaster with the 3.6L Pentastar engine requires careful attention to detail.

Coil-on-Plug Removal

Your ProMaster uses a coil-on-plug (COP) ignition system. Each spark plug has its own individual ignition coil mounted directly above it. To remove them:

1. Disconnect: Carefully disconnect the electrical connector from each coil. There