A Guide to Spark Plugs for the 2019-2024 GMC Terrain
If your GMC Terrain is running rough or losing power, worn spark plugs could be the reason.
- For 1.5L engines, be aware of the TSB regarding cracked ceramic insulators on original plugs causing misfires.
- Always use Iridium spark plugs from a quality brand like ACDelco, NGK, or Bosch for best performance.
- Do not attempt to re-gap new Iridium spark plugs; they are pre-set and can be easily damaged.
- Replacing spark plugs is a simple DIY task on the 2019-2024 Terrain that can be done in under an hour.
Is Your Terrain Showing Signs of Bad Spark Plugs?
When spark plugs wear out, they can't create a strong enough spark to burn the fuel efficiently. This can cause a number of noticeable problems. Watch for these common symptoms in your 2019-2024 GMC Terrain.
- Rough Idle: The engine may shake or vibrate more than usual when you're stopped at a light.
- Engine Misfires: You might feel a hesitation, stumble, or jerking sensation during acceleration.
- Check Engine Light: A failing spark plug is a common reason for the check engine light to come on. You may see codes like P0300 (for a random misfire) or P0301-P0304 (for a misfire in a specific cylinder).
- Poor Acceleration: The vehicle may feel sluggish or less responsive when you press the gas pedal.
- Worse Fuel Economy: If you're filling up your gas tank more often, inefficient combustion from bad plugs could be the cause.
Known Issue for 1.5L Engines: Cracked Spark Plugs
General Motors issued a Technical Service Bulletin (TSB #PIP5642) for some 2018-2019 GMC Terrains with the 1.5L engine that experienced rough running and misfire codes. The investigation found that the ceramic insulator on the original spark plugs could crack, preventing a proper spark. If you have a 1.5L engine and experience these symptoms, it is highly recommended to inspect the plugs for cracks and replace them as a set.
Choosing the Right Aftermarket Spark Plugs
For a modern turbocharged engine like the one in your Terrain, the type and quality of the spark plug matter. Always choose an Iridium spark plug, as this is what the vehicle was designed with. Copper or standard platinum plugs are not recommended.
Brand Quality Tiers
- OEM (Original Equipment): ACDelco is the original GM parts brand. Choosing ACDelco Iridium plugs guarantees a perfect fit and performance identical to the factory parts. This is the safest and most recommended choice.
- Premium Aftermarket: Brands like NGK and Bosch are top-tier choices. NGK is a world-renowned spark plug manufacturer and their Iridium IX series is considered by many to be an upgrade over stock for performance and durability. Bosch Double Iridium plugs are also an excellent, reliable alternative.
- Standard Aftermarket: Autolite and Champion offer Iridium plugs that provide good performance and value. These are dependable options that meet the requirements for your Terrain's engine.
Pro Tip: Do Not Adjust the Gap on Iridium Plugs
ACDelco, NGK, and other Iridium spark plugs for your Terrain come pre-gapped from the factory. The iridium tip is very fine and can be easily damaged if you try to adjust the gap. Always verify you have the correct part number for your vehicle and install them directly out of the box without gapping.
Cost to Replace GMC Terrain Spark Plugs
| Part Type | Price Range (Set of 4) |
|---|---|
| New Aftermarket (Iridium) | $43 - $83 |
| New OEM (ACDelco Iridium) | $50 - $90 |
| Shop Labor | $90 - $180 |
Frequently Asked Questions
How often should I replace the spark plugs on my GMC Terrain?
The typical replacement interval for original equipment iridium spark plugs is between 60,000 and 100,000 miles. However, if you experience any failure symptoms, you should have them checked sooner.
Can I install the spark plugs myself?
Yes, this is a DIY-friendly job for someone with basic tools. The spark plugs and ignition coils on both the 1.5L and 2.0L four-cylinder engines are located on top of the engine and are easy to access after removing the plastic engine cover. The job typically takes less than an hour.
What is an engine misfire?
A misfire occurs when one of the engine's cylinders fails to ignite the air-fuel mixture correctly. This can be caused by a bad spark plug, a faulty ignition coil, or a fuel delivery problem. It disrupts the engine's rhythm, causing the shaking and hesitation you feel.
What happens if I don't replace my bad spark plugs?
Continuing to drive with a misfire can cause unburned fuel to enter the exhaust system. This can overheat and damage the catalytic converter, which is a very expensive repair. It will also lead to poor performance, bad fuel economy, and will cause your vehicle to fail an emissions test.
Helpful Videos
Technical Specifications
OEM Part Numbers: ACDelco 41-156 ACDelco 41-125 GM 12681660 GM 12683541
Material: Iridium. Gap: Pre-gapped from the factory, do not adjust.
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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.
- GMC Terrain:
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- Is Your Terrain Showing Signs of Bad Spark Plugs?
- Known Issue for 1.5L Engines: Cracked Spark Plugs
- Choosing the Right Aftermarket Spark Plugs
- Brand Quality Tiers
- Pro Tip: Do Not Adjust the Gap on Iridium Plugs
- Cost to Replace GMC Terrain Spark Plugs
- Frequently Asked Questions
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