2020 Jeep Wrangler Spark Plug Guide

Quick Reference: Spark Plug Specifications

Note: The 3.0L EcoDiesel engine does not use spark plugs; it uses glow plugs for cold starts. This guide focuses on the gasoline engines.

Why the Right Spark Plug Matters

Choosing the correct spark plug is crucial for engine performance, fuel economy, and longevity. The engineers who designed your Wrangler's engine selected a very specific plug for a reason, considering factors like heat range and electrode material.

• Heat Range: This refers to the plug's ability to dissipate heat from the combustion chamber. A plug that is too "hot" can overheat and cause pre-ignition (detonation), which can severely damage the engine. A plug that is too "cold" can run too cool, leading to carbon fouling and misfires. The factory-specified NGK plugs are designed with the precise heat range for the 2.0L Turbo and 3.6L V6 engines.

• Electrode Material: The 2020 Wrangler engines come equipped from the factory with iridium-tipped spark plugs. Compared to older copper or even platinum plugs, iridium offers superior durability and performance. Its extremely high melting point allows for a very fine center electrode, which requires less voltage to create a spark. This results in a more consistent and stable spark, improving throttle response and fuel efficiency. While copper plugs are cheaper, they wear out much faster and are not recommended for these modern engines. Stick with the specified iridium plugs to maintain performance and enjoy the long 100,000-mile service interval.

How to Gap a Spark Plug

Even when buying pre-gapped plugs, it is essential to verify the gap before installation. Plugs can be dropped during shipping, causing the gap to close.

1. Use the Right Tool: Use a dedicated spark plug gapper, such as a feeler gauge or a wire-loop style tool. Do not use the edge of a coin or a cheap disc-style gauge, as these can damage the fragile iridium tip.
2. Measure: For both the 2.0L and 3.6L engines, the correct gap is 0.043 inches (1.1mm). Gently slide the gauge between the center and ground electrodes. It should have a slight drag but not be too tight or too loose.
3. Adjust Carefully: If the gap is incorrect, make adjustments by gently bending the ground strap (the curved piece of metal over the center electrode). Use the tool's adjustment slot to carefully pry it open or press it gently against a hard surface to close the gap. Never pry against or touch the center electrode.

Replacement Procedure Tips

Replacing the plugs on your 2020 Wrangler is straightforward, as both engines use a modern coil-on-plug (COP) ignition system. This means each spark plug has its own ignition coil sitting directly on top of it, eliminating the need for old-school distributor caps and spark plug wires.

• Coil-on-Plug Removal: Begin by disconnecting the negative battery terminal. To access a plug, you must first remove its ignition coil. Unplug the low-voltage connector, then undo the single bolt holding the coil to the valve cover (typically an 8mm or 10mm bolt). The coil can then be gently twisted and pulled straight up. The rubber boot can create a seal, so some firm effort may be needed.

• The Anti-Seize Debate: The use of anti-seize compound on spark plug threads is a topic of much debate. However, major manufacturers like NGK advise against using it on their modern plugs. These plugs have a special trivalent plating that acts as its own anti-seize and release agent. Applying additional lubricant can alter the torque reading, leading you to over-tighten the plug, which can stretch the threads and damage the cylinder head. We recommend installing the plugs dry, per the manufacturer's instructions.

• Dielectric Grease: While anti-seize is not recommended on the threads, applying a small amount of dielectric grease to the inside of the ignition coil boot is a best practice. This grease prevents the boot from sticking to the spark plug porcelain over time and helps seal out moisture, preventing corrosion on the terminal.

Known Issues

While older engine designs (like Ford's 3-valve Triton engines) were notorious for difficult-to-remove spark plugs that could break off in the cylinder head, the 2.0L and 3.6L engines in the 2020 Jeep Wrangler are not known for this issue. The design is robust and, when serviced correctly, provides reliable performance. Always work on a cold engine and tighten plugs to the specified torque to avoid any problems.

Need plugs replaced? Find a shop on Repairius.