2025 Chevrolet Malibu Spark Plug Spec Guide: Type, Gap & Torque

As an ASE-certified master technician, I’ve serviced countless modern engines, and the 1.5L turbocharged engine in the 2025 Chevrolet Malibu is a prime example of a powertrain where exact maintenance matters. Modern turbocharged, direct-injected engines rely heavily on a strong, perfectly timed spark to avoid misfires and pre-ignition.

If you are gearing up for a tune-up on your 2025 Malibu, you need to ensure you have the exact OEM-specified spark plugs, the correct gap, and the proper torque values. Below is everything you need to know to get the job done right.

Quick reference

Note: The 2.0L engine is no longer offered in the 2025 Malibu lineup.

Why the right plug matters

Choosing the correct spark plug is more than just making sure the threads fit. The 2025 Malibu's 1.5L engine demands an Iridium spark plug.

• Electrode Metal: Iridium is incredibly hard and handles the extreme combustion chamber temperatures of a turbocharged engine much better than traditional copper or platinum. While copper conducts electricity well, it degrades rapidly under forced induction. Standard platinum cannot withstand the heat cycle quite as well as iridium.
• Heat Range: The heat range dictates how fast the spark plug pulls heat away from the firing tip and transfers it into the cylinder head. Using a plug with the wrong heat range can result in carbon fouling (if too cold) or pre-ignition and engine damage (if too hot). Always stick to the OEM heat range specified by ACDelco or equivalent NGK/Denso cross-references.

How to gap a spark plug

Most Iridium spark plugs, including the ACDelco 41-156, come pre-gapped from the factory. However, shipping and handling can sometimes alter the gap, so it is crucial to verify it before installation.

1. Use a wire-style gauge: For delicate iridium tips, a wire-style gap tool or feeler gauge is much safer than the traditional coin-style ramp tool.
2. Measure carefully: Gently slide the 0.028-inch wire between the center and ground electrode. There should be a slight drag.
3. Adjusting (if necessary): Never pry against the center iridium electrode—it will snap. If you need to open the gap, use the bending notch on your gap tool to gently bend the ground strap outward.

Replacement procedure tips

The 1.5L Malibu utilizes a Coil-on-Plug (COP) ignition system. The procedure is highly accessible right on top of the valve cover, but a few best practices apply:

• Coil-on-plug removal: Remove the 10mm retaining bolt holding the ignition coil. Gently twist the coil boot back and forth before pulling straight up to break the seal without tearing the rubber boot.
• The Anti-Seize Debate: Do not use anti-seize on the threads of new ACDelco or NGK plugs. Modern premium spark plugs feature a specialized trivalent metal plating that prevents seizing in the aluminum cylinder head. Adding wet anti-seize alters the friction coefficient, which can easily cause you to over-torque the plug and strip the threads.
• Dielectric Grease: Apply a small pea-sized amount of dielectric grease to the inside tip of the coil boot. This prevents moisture intrusion, stops high-voltage tracking (arcing), and prevents the rubber from fusing to the ceramic insulator of the spark plug over the next 60,000 miles.

Known issues

While you won't have to deal with the infamous broken plug shells found on early 2000s Ford 3-valve engines, the Chevy 1.5L turbo engine does have its quirks.

Because this is a small-displacement turbocharged and direct-injected (TGDI) engine, it is highly susceptible to Low-Speed Pre-Ignition (LSPI). A degraded, worn-out spark plug with an eroded gap can contribute to erratic combustion and misfires. In TGDI engines, severe misfires and LSPI can lead to cracked pistons. Sticking to the strict 60,000-mile replacement interval is non-negotiable to protect the engine’s internal components. Additionally, GM ignition coils on these engines are sensitive; if a plug's resistance gets too high due to wear, it can burn out the coil pack prematurely.

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