A Guide to Spark Plug Replacement for the Mercedes-Benz GL450 (2007-2016)
Keep your GL450's V8 engine running strong by choosing the right spark plugs for your specific model year.
- The recommended service interval is typically 60,000 miles, but consider replacing sooner on twin-turbo models (2013-2016).
- Stick to high-quality aftermarket brands like Bosch, NGK, or Denso, which are often the OEM suppliers.
- Identify your engine (M273 for 2007-2012, M278 for 2013-2016) to ensure you purchase the correct spark plugs.
- Continuing to drive with misfiring plugs can damage expensive components like ignition coils and catalytic converters.
Symptoms of Failing Spark Plugs
When your GL450's spark plugs are nearing the end of their life, your vehicle will often let you know. Ignoring these signs can lead to reduced performance, poor fuel economy, and potentially more expensive repairs down the road. Common symptoms include a rough idle, engine hesitation during acceleration, a noticeable drop in gas mileage, and difficulty starting the engine. In many cases, a worn-out spark plug will trigger the Check Engine Light, often with codes indicating an engine misfire (P0300-P0308).
Choosing the Right Aftermarket Spark Plugs
When it's time for a replacement, you have options outside of the dealership. For the GL450, using a high-quality aftermarket spark plug from a reputable brand is a smart choice that can offer the same performance as original equipment (OE) parts without the higher price tag.
Engine Differences Matter
It is critical to know which engine your GL450 has, as this affects which spark plugs you need. The 2007-2012 models are equipped with the naturally aspirated M273 V8 engine, while the 2013-2016 models feature the more complex M278 twin-turbo V8. Always verify part fitment for your specific year before purchasing.
Aftermarket Brand Tiers
- Top Tier (OEM-Equivalent): Brands like Bosch and NGK are often the original equipment manufacturers for Mercedes-Benz. Choosing their Iridium or Platinum plugs ensures you get factory-level performance, durability, and fit. Many owners and mechanics prefer these brands for their reliability in German engines.
- Quality Alternatives: Denso is another excellent Japanese brand known for high-quality Iridium plugs that offer a long service life and consistent performance.
- Budget-Friendly Options: Brands like Autolite and Champion offer more affordable spark plugs. While they can get the job done, they may not offer the same longevity or precise performance characteristics required by the high-performance V8 engines in the GL450, potentially leading to a shorter replacement interval.
Pro Tip: Many modern spark plugs from brands like Bosch come pre-gapped and have nickel-plated threads that do not require anti-seize compound. Applying anti-seize can lead to over-torquing and damage to the plugs or engine.
Known Issues, Recalls, and Service Bulletins
Searches for official recalls from the National Highway Traffic Safety Administration (NHTSA) did not find any spark plug-specific recalls for the 2007-2016 GL450. However, some owners on forums have reported issues with the ceramic insulator on the original plugs breaking down over time, leading to misfires. This makes sticking to the recommended replacement interval important. There are no known Technical Service Bulletins (TSBs) directly related to spark plug failure for this vehicle range.
| Part Type | Price Range (Set of 8) |
|---|---|
| New Aftermarket | $33 - $296 |
| New OEM | $117 - $320 |
| Shop Labor | $257 - $377 |
Frequently Asked Questions
How often should I replace the spark plugs on my GL450?
The recommended replacement interval for a Mercedes-Benz GL450 is typically every 60,000 miles or every 6 years, whichever comes first. However, for the twin-turbo M278 engine (2013-2016), some sources recommend a shorter interval of 40,000 to 50,000 miles due to the higher stress from the turbochargers.
What is the difference between Iridium and Platinum spark plugs?
Both Iridium and Platinum are precious metals used on the tip of the spark plug's electrode to increase durability and performance. Iridium is harder and has a higher melting point than platinum, which generally allows for a longer service life and a more consistent spark over many miles. For the GL450, either Double Platinum or Iridium plugs from a top-tier brand are recommended.
Is replacing the spark plugs a DIY job?
For an experienced DIYer, yes. The job is more straightforward on the 2007-2012 M273 engine, often described as one of the easier V8 spark plug jobs. The 2013-2016 M278 engine is more complex due to the turbochargers and associated plumbing. You will need a specific 5/8" or 14mm thin-wall spark plug socket, a torque wrench, and various extensions and Torx sockets.
Should I replace the ignition coils at the same time?
It is not required to replace the ignition coils with the spark plugs. However, a failing spark plug can put extra strain on its corresponding ignition coil, potentially causing it to fail sooner. If you are diagnosing a misfire and find a bad coil, it is wise to replace all spark plugs at the same time if they are near their service interval.
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Technical Specifications
OEM Part Numbers: 0041598103 0041596803 0041596403 0041594903 2701590600
The 2007-2012 GL450 (M273 engine) and 2013-2016 GL450 (M278 engine) use different spark plugs. Both are V8 engines requiring 8 plugs. A 5/8-inch or 14mm thin-wall magnetic spark plug socket is required for replacement. Torque spec is approximately 23 Nm.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Mercedes-Benz GL450: