2021 Jeep Cherokee Spark Plug Type & Gap Guide

Quick reference

Why the right plug matters

Choosing the correct spark plug for your 2021 Jeep Cherokee is more critical than you might think. Spark plugs are not a universal component; they are precision-engineered for specific engines. Using the wrong plug can lead to a host of problems, from reduced fuel economy and diminished performance to misfires, engine damage, and even catalytic converter failure.

Key factors to consider include the heat range and the electrode metal.

• Heat Range: This refers to the plug's ability to dissipate heat. A "cold plug" dissipates heat quickly and is suitable for high-performance engines that run hotter. A "hot plug" retains more heat in its firing tip and is used in engines that tend to run cooler, helping to burn off carbon deposits. Using a plug with an incorrect heat range can lead to pre-ignition, detonation, or rapid fouling.
• Electrode Metal:
  • Iridium: These are the most common OEM choice for modern vehicles like the 2021 Jeep Cherokee. Iridium is extremely hard and has a very high melting point, allowing for very fine electrodes. This results in a more focused and stable spark, longer service life (typically 100,000 miles or more), and improved ignitability.
  • Platinum: Platinum plugs offer good durability and performance, often lasting around 60,000-80,000 miles. They are a step up from copper but not as long-lasting or efficient as iridium.
  • Copper: While still used in some older or specialized applications, copper has excellent conductivity but wears down much faster due to its softer nature. Copper plugs typically require replacement every 30,000 miles or less.

Both the 2.4L Tigershark and 3.2L Pentastar engines in the 2021 Jeep Cherokee are designed to run with iridium spark plugs due to their advanced ignition systems and longer service intervals.

How to gap a spark plug

Correct spark plug gap is crucial for optimal engine operation. The gap dictates the distance the spark must travel, influencing the strength and consistency of the ignition.

For your 2021 Jeep Cherokee, both engine options specify a gap of 0.043 inches (1.1 mm).

Tools needed: A wire-type spark plug gapping tool. A disc-style gapper can damage fine-wire iridium or platinum electrodes.

Procedure:

1. Check the gap: Carefully slide the appropriate wire gauge from your tool between the center and ground electrodes. It should slide in with a slight drag.
2. Adjusting the gap (if necessary): If the gap is too small, use the gapping tool's adjustment arm to gently pry the ground electrode slightly away from the center electrode. If the gap is too wide, gently tap the ground electrode on a clean, hard surface to close it very carefully.
3. Re-check: Always re-check the gap after adjustment. Be extremely gentle with iridium and platinum plugs, as the fine electrodes can be easily damaged.

Replacement procedure tips for the 2021 Jeep Cherokee

Replacing spark plugs on your 2021 Jeep Cherokee is a manageable DIY task for most, but here are some specific tips:

• Engine Cool-Down: Always perform spark plug replacement on a completely cold engine. Removing plugs from a hot aluminum cylinder head can strip the threads.
• Coil-on-Plug System: Both the 2.4L Tigershark and 3.2L Pentastar engines utilize a coil-on-plug (COP) ignition system. This means each spark plug has its own ignition coil directly mounted above it. To access the plugs, you'll need to carefully disconnect the electrical connector from each coil and then undo the bolt(s) securing the coil to the valve cover. Gently twist and pull to remove the coil.
• Anti-Seize Debate: There is ongoing debate about using anti-seize on spark plug threads. Modern spark plugs, especially those from NGK and Denso, often have a specialized coating on their threads that acts as an anti-seize. Applying additional anti-seize can lead to over-torquing the plugs, as the anti-seize acts as a lubricant, reducing friction. For the 2021 Jeep Cherokee, it is generally recommended not to use anti-seize if the plugs have a silver or shiny coating on the threads. If the threads are bare or black, a tiny amount of anti-seize can be applied, but reduce the torque setting by about 10-15%. However, strictly following the manufacturer's torque specification with coated plugs is best.
• Dielectric Grease on Boots: A small dab of dielectric grease inside the spark plug boot (the end that connects to the spark plug) can help prevent moisture intrusion and makes future removal easier. Apply it sparingly – you don't want it on the electrode or inside the coil spring.
• Proper Tools: Use a dedicated spark plug socket (typically 5/8" or 16mm, depending on the plug) with a rubber insert to protect the porcelain insulator and help grip the plug during removal and installation. A torque wrench is essential to ensure you meet the specified torque of 18 lb-ft (24 Nm).
• Order of Operations: Replace one spark plug at a time. This prevents mixing up ignition coils and ensures no foreign objects fall into the combustion chamber.

Known Issues

Fortunately, the 2021 Jeep Cherokee, with its 2.4L Tigershark and 3.2L Pentastar engines, does not have any widespread or notorious spark plug-related issues akin to the Ford 3-valve 2-piece spark plug breakage or GM 5.3L ionization-sensing coil problems. As long as the correct OEM or recommended aftermarket plugs are used and replaced at the specified intervals, you should expect trouble-free operation.

Need plugs replaced? Find a shop on Repairius.