When should you replace spark plugs?
Does your petrol car start with difficulty, idle roughly or judder when you pull away? Then your spark plugs are a logical suspect. Spark plugs ignite the fuel-air mixture in your engine and wear gradually — so you often only notice once it's been going on for a while. Worn plugs cause hard starting, loss of power and higher fuel use, and can trigger the engine warning light. This guide explains what spark plugs do, when to replace them per the manufacturer's interval and which signs point to wear. AutoJet in Almere reads the fault codes and fits the correct plugs — you see the price up front by license plate. Open Mon–Sat 11:00–20:00.
What do spark plugs actually do?
In a petrol engine, spark plugs have one crucial job: at exactly the right moment, to deliver a spark that ignites the fuel-air mixture. That small explosion in the cylinder pushes the piston down — and that's what makes your car run. Each cylinder has its own plug, so most cars have four.
When a plug no longer works well, the spark gets weaker or sometimes drops out. The mixture then burns incompletely or not at all, and you notice it straight away: the engine is harder to start, runs roughly and loses power. Good spark plugs are therefore the basis of a smooth-running petrol engine.
When should you replace spark plugs?
The replacement interval is set per the manufacturer's schedule in your service book and differs by car and by type of plug. As a rule of thumb you're usually between 30,000 and 90,000 km: standard plugs last shorter, while iridium or platinum plugs last considerably longer. Not sure? Enter your license plate and we'll see which plugs your car needs and what the schedule says.
Note: diesel engines don't have spark plugs — they ignite the mixture by compression and use glow plugs to start, which is something entirely different. This guide is about the spark plugs of a petrol engine. If you drive a diesel and have starting trouble, have the fault codes read so we find the real cause.
Signs of worn spark plugs
Spark plugs wear slowly, so most drivers get used to the deteriorating engine behaviour without noticing. Recognise one of these signs? Have the fault codes read:
- Hard or irregular starting — the engine only fires after a few attempts.
- Rough idle — the engine shakes or runs unevenly when stationary.
- Misfire or judder — the engine briefly misses (misfire) when pulling away.
- Loss of power — the car accelerates more slowly than you're used to.
- Higher fuel use — you refuel noticeably more often without driving differently.
- Engine warning light — a weak or misfiring plug can trigger a fault code.
What does it cost to replace your spark plugs?
We start by reading the fault codes so we're sure the plugs are the cause and not something else. Then we replace the plugs — usually four — including the plugs themselves. You see the price up front by license plate, so you're never caught out:
| Service | Price |
|---|---|
| Diagnostic read free with repair | €70 |
| Replace spark plugs (incl. plugs, usually 4) incl. fitting | from €99 |
| Labour | €70 / hour |
| Exact price | by license plate |
The final price depends on your car — enter your license plate and you'll see it up front. You never pay for work you haven't approved in advance.
How AutoJet helps: read codes, correct plugs, price up front
Not sure whether your spark plugs are due for replacement? At AutoJet in Almere we read the fault codes first, so we're sure it's the plugs and not, say, the coils or injectors. That way you don't replace anything needlessly.
If replacement is needed, we fit the correct plugs for your engine — the type the manufacturer specifies. Enter your license plate and we see the make and model and give you a clear price up front. We speak Ukrainian, Russian and English — handy if Dutch isn't your first language.
See also: Spark plug replacement in Almere · Blog
Frequently asked questions about replacing spark plugs
When should I replace my spark plugs?
That's set per the manufacturer's schedule in your service book and differs by car. As a rule of thumb usually between 30,000 and 90,000 km: standard plugs last shorter, iridium or platinum plugs considerably longer. Enter your license plate at AutoJet in Almere and we'll see which plugs your car needs.
How do I recognise worn spark plugs?
The clearest signs: the engine starts hard or irregularly, idles roughly, judders when pulling away, loses power, uses more fuel or the engine warning light is on. Recognise one? Have the fault codes read at AutoJet in Almere.
Do diesel cars have spark plugs too?
No. Diesel engines don't have spark plugs — they ignite the mixture by compression and use glow plugs to start from cold, which is something entirely different. This guide is about the spark plugs of a petrol engine. If you have starting trouble with a diesel, have the fault codes read so we find the real cause.
What does replacing spark plugs cost at AutoJet?
We replace spark plugs from €99, including the plugs themselves (usually four) and fitting. Reading the fault codes costs €70 and is free with a repair. Labour is €70 per hour and you see the exact price up front by license plate. You never pay for work you haven't approved.
Can you keep driving with worn spark plugs?
You can for a while, but it's not wise. A misfiring plug lets unburnt fuel through, which over time can damage the catalytic converter — a far more expensive repair. On top of that you drive with higher fuel use and less power. Replacing in time is therefore cheaper.
Do you read the fault codes first?
Yes. We read the fault codes first to be sure it's the plugs and not, say, the coils or injectors. That way you don't replace anything needlessly. If replacement is needed, you get a clear price up front by license plate — and then you decide.
Engine running rough? Have the fault codes read.
Fault codes read €70 (free with repair) · spark plugs from €99 · price up front by license plate