You should change spark plugs based on your vehicle's manual, typically every 30,000 to 100,000+ miles (50,000 to 160,000+ km) for modern cars, depending on plug type (copper lasts less, iridium/platinum last longer), but watch for signs like poor acceleration, rough idling, misfires, or decreased fuel economy, as these signal an urgent need for replacement, often to prevent damage to your catalytic converter.
You should always refer to your owner's manual for specific information on your vehicle. However, the majority of auto manufacturers suggest having new spark plugs installed every 30,000 miles. The actual longevity of the spark plug can range based on the type and conditions.
For most vehicles, replacing spark plugs takes 30 minutes to two hours. If your engine layout allows easy access to the spark plugs, the process is relatively quick.
Most manufacturers recommend replacing spark plugs every 50,000 kilometres, but spark plug quality varies. Some last around 130,000 kilometres, while cheap plugs made of copper may last approximately 40,000 kilometres. “Extended life” spark plugs made of more resilient metals can last up to 160,000 kilometres.
Delaying spark plug replacement beyond 60000 miles can lead to fouled plugs, causing engine misfires, rough idling, and poor acceleration. Worn plugs increase ignition gap, reducing combustion efficiency and fuel economy. To avoid damage, inspect plugs regularly for carbon buildup or electrode wear.
Standard copper and nickel-based models need to be changed every 30,000 to 50,000 miles unless otherwise specified by the manufacturer. On the other hand, platinum or iridium spark plugs may last as long as 60,000-150,000 miles before they require replacement.
The exact time it takes for an engine to cool down completely can vary. Some might take one to two hours, while others can take more than four hours to revert to their ambient temperature, depending on how hot or old it is outside. Low coolant, radiator issues, and thermostat failure can cause an engine to overheat.
Bad spark plug symptoms include rough idling, engine misfires, difficulty starting, sluggish acceleration, poor fuel economy, and the check engine light coming on, all stemming from the plug's failure to properly ignite the air-fuel mixture, leading to inefficient combustion and performance issues.
Replacing your spark plugs will help ensure your engine runs efficiently, saving you money at the pump. Another benefit of replacing your spark plugs is improved engine performance. With lousy spark plugs, you might experience misfires when they fail to ignite the air-fuel mixture.
Spark plugs are small electrical devices in the engine that ignite the air-fuel mixture, creating combustion to power your vehicle. They usually last around 80,000 miles and are typically changed during routine, regularly scheduled maintenance according to the manufacturer's recommendations.
Replacing your spark plugs is actually a relatively simple DIY task. However, it is important to make sure you have the correct tools and follow the proper steps.
How much does a spark plugs replacement cost in 2025? A typical spark plugs replacement cost in the UK is around £15 - £72. Depending on your car brand, model and engine, and whether you live in a big city or a small one, the price of a spark plugs replacement on your vehicle can be higher or lower.
Worn spark plugs could be to blame if you notice a significant decrease in engine power or sluggish acceleration. Faulty spark plugs can lead to inefficient combustion, resulting in reduced engine power and slower acceleration response, especially when attempting to accelerate quickly or climb steep inclines.
Below are some signs your spark plugs may need to be replaced.
Overheating. Repeated overheating of the spark plug tip can cause the plug to prematurely fail. Overheating can be caused by many things like pre-ignition and a malfunctioning cooling system. Pre-ignition can lead to heat building up in the combustion chamber causing the spark plugs to fail.
Yes, a bad spark plug can cause misfires, resulting in rough running, poor performance, and engine damage. It's essential to replace faulty spark plugs promptly.
Fresh spark plugs contribute to smoother acceleration and improved power delivery. If your vehicle starts feeling sluggish or as though it cannot deliver power as well as before, replacing the plugs can help solve these issues.
Replacing your spark plugs can help improve your car's fuel efficiency. Strong spark plugs ignite the air-fuel mixture and churn fuel to start combustion. Spark plugs become less efficient with time. However, changing them prevents this and restores the car's fuel efficiency, gas mileage, and fuel economy.
SLUGGISH ACCELERATION: A telltale sign your vehicle may have a spark plug issue is sluggishness upon acceleration. If you feel like your vehicle just isn't as responsive as it used to be, this may be the problem. It is often a result of the park plug being unable to ignite the air-fuel mixture in a consistent pattern.
A multimeter reading between 5 and 15 when touching the terminal end and the top of the central electrode indicates that your spark plug is in good shape. If there's no reading, the metal running insulated between these two points might be broken.
7 Signs of a Faulty Ignition Coil
Rough idling
A fouled spark plug causes your engine to sound rough while idling.
Oil and coolant circulate around the idling engine at a slower rate. They remove less heat, leading to the engine running. An idling vehicle also has a higher air intake temperature.
Answer: Your car engine could stay warm for several hours after turning it off, especially if it's hot outside. But if your engine is still hot—not just warm—after two hours, there's a good chance it was overheating when you shut it down.
Spark Plugs Should Be Changed When The Engine Is At An Ambient Temperature.