How often should spark plugs be replaced and how much does it cost in 2026, including LPG?

indekscen.pl editorial team · published 30 September 2026 · prices according to the 5 October 2026 index

Standard spark plugs are usually replaced every 30,000 to 60,000 km, and iridium or platinum plugs every 60,000 to 120,000 km. In an LPG car, they should be replaced roughly twice as often. Labour most commonly costs PLN 160 (typically PLN 105 ‑ 200), while the set of plugs is purchased separately.

Spark plugs are inexpensive parts, but when they wear out, the engine begins to judder, consumes more fuel and wears out the coils faster. The question of how often they should be replaced is therefore more important than how much it costs: missing a replacement can cost several times more than scheduled maintenance. We have compiled typical intervals and labour prices from garage price lists.

How often should spark plugs be replaced?

Spark plugs should be replaced every 30,000 to 60,000 km if they are standard nickel plugs, and every 60,000 to 120,000 km for iridium or platinum plugs. The interval in your car’s service manual takes precedence, as manufacturers set it for the specific engine. Turbocharged direct-injection engines often have shorter intervals than older naturally aspirated engines.

If you do not know which plugs your car has, check the last invoice from the garage or ask the mechanic during a service. If the service history is unknown, for example after buying a used car, it is sensible to replace the plugs straight away.

Type of spark plug and fuel	Typical replacement interval
Nickel spark plugs, petrol	from 30,000 to 60,000 km
Iridium or platinum spark plugs, petrol	from 60,000 to 120,000 km
Nickel spark plugs, LPG	from 15,000 to 30,000 km
Iridium spark plugs, LPG	from 30,000 to 60,000 km

How often should spark plugs be replaced in an LPG car?

In an LPG car, spark plugs should be replaced roughly twice as often as in the same engine running on petrol, usually every 15,000 to 30,000 km. Gas burns at a higher temperature and requires a stronger spark, so the electrodes wear out faster. Mechanics often recommend iridium plugs or plugs designed for LPG, which last longer.

The simplest approach is to combine spark plug replacement with the mandatory annual LPG system inspection, which usually costs PLN 145 ‑ 170. The technician will be checking how the engine runs on gas anyway and may notice misfires. We discuss the cost of the tank and its certification in the article LPG tank certification or replacement.

How much does spark plug replacement cost: labour price

Labour for replacing spark plugs most commonly costs PLN 160, according to 6 price lists and articles collected by indekscen.pl, while half of the prices fall within PLN 105 ‑ 200. A full breakdown of prices and sources is available at spark plug replacement.

Prices vary widely, from PLN 35 to PLN 350, because the engine design determines the labour time:

1. Number of cylinders. A V6 or V8 has six or eight plugs instead of four.
2. Access to the plugs. On some engines, the intake manifold or covers must be removed, turning a 15-minute job into several hours of work.
3. Garage labour rate. The median hourly labour rate at an independent garage is PLN 175, and much higher at an authorised dealership. We compare them in the article mechanic’s hourly labour rate: independent garage or authorised dealership.
4. Type of spark plug. Standard plugs are inexpensive, while iridium plugs cost several times more but require less frequent replacement.

Our index does not include the prices of the spark plugs themselves, so we do not show them in the table. Below is a comparison of services that are often carried out together:

Median and typical range from public price lists, as at 5 October 2026. Each price includes a source and quotation on the service page.

How long does spark plug replacement take?

Replacing spark plugs in a typical four-cylinder engine takes 15 to 30 minutes, while engines with difficult access take one to three hours. The job takes longest in V6 engines where the rear plugs are hidden beneath the manifold. If a garage quotes several hours of labour for a standard four-cylinder car, ask exactly what the service includes.

How can you tell when spark plugs need replacing?

Spark plugs need replacing when the engine is difficult to start, judders during acceleration or runs unevenly at idle. Typical symptoms include:

• difficulty starting, especially in the morning and in winter,
• juddering and loss of power during acceleration,
• higher fuel consumption with no other apparent cause,
• a flashing engine warning light, which indicates a misfire.

A flashing warning light means that the engine is misfiring in one of its cylinders. The cause may be a spark plug, but it could also be a coil or injector. Computer diagnostics costing around PLN 165 will identify the cylinder and help avoid replacing parts unnecessarily.

Should ignition coils be replaced along with spark plugs?

Ignition coils do not need to be replaced every time the spark plugs are changed, only when they are faulty. In most newer engines, each coil sits directly on a spark plug, so the mechanic removes it anyway and can check it. A separate ignition coil replacement usually costs PLN 150 ‑ 340 per coil, depending on whether the price includes the part.

However, it is worth replacing the spark plugs when a coil fails: a worn plug with a large electrode gap requires a higher voltage and accelerates the failure of the new coil.

What are the benefits of replacing spark plugs?

Replacing worn spark plugs restores smooth engine operation, easier starting and normal fuel consumption. New plugs will not increase power beyond the factory specification, but the difference can be noticeable in a car whose plugs are tens of thousands of kilometres overdue. In an LPG car, new plugs reduce the risk of misfires, which can damage the catalytic converter when running on gas.

Can you replace spark plugs yourself?

You can replace the spark plugs yourself in a simple four-cylinder engine if you have a spark plug socket and torque wrench, and access to the plugs does not require removing the manifold. This saves the labour cost, usually PLN 105 ‑ 200. There is one risk, but it can be costly: stripping or cross-threading the thread in the aluminium cylinder head.

If you do the job yourself, follow these rules:

1. Work only on a cold engine.
2. Before removing the plugs, blow compressed air into the plug wells to prevent dirt from falling into the cylinders.
3. Screw in each new plug by hand first, and only then use a tool.
4. Tighten the plug to the torque specified by the spark plug manufacturer, rather than guessing.
5. Replace the plugs one at a time to avoid mixing up the leads or coils.

If a plug resists removal, stop working and take the car to a garage. A seized plug that snaps in the cylinder head can cost many times more to repair than a standard replacement.

How can you avoid overpaying for spark plug replacement?

• Combine the replacement with other work. During a service, oil change or LPG system maintenance, the cost of bringing in and booking the car has already been covered.
• Ask for the price for the full set, not per plug. Some price lists quote a rate per item.
• Buy plugs listed in the car manufacturer’s catalogue, rather than simply choosing the ‘best’ ones in the shop. The wrong spark plug heat range can damage the engine.
• Ask to see the old plugs. Their appearance tells the mechanic a great deal about how the engine is running, including whether it is burning oil.

It is worth recording scheduled replacements alongside other service intervals, such as the timing belt interval discussed in the article how often should the timing belt be replaced?. You can find more repair prices in the motoring category.

The prices in this article come from publicly available garage price lists and motoring articles. Each price on the how much does spark plug replacement cost? page includes its source, date and a verbatim quotation.

Frequently asked questions

How much does a mechanic charge to replace spark plugs?

Robocizna za wymianę kompletu świec zapłonowych to mediana PLN 160, a połowa warsztatów liczy PLN 105 ‑ 200. Świece są doliczane osobno.

How much does it cost to replace 4 spark plugs?

Cztery świece to typowy silnik czterocylindrowy, w którym robocizna kosztuje zwykle od PLN 35 do mediany PLN 160. Wyżej płaci się tylko wtedy, gdy trzeba zdjąć kolektor dolotowy.

What damages spark plugs fastest?

Świece najszybciej niszczy jazda na gazie, źle wyregulowana mieszanka, olej przedostający się do komory spalania i krótkie trasy na zimnym silniku. Uszkodzona cewka też przyspiesza zużycie świecy, a jej wymiana kosztuje zwykle PLN 150 ‑ 340.

Should spark plugs be replaced when the engine is warm or cold?

Świece zapłonowe wymienia się na zimnym silniku, bo aluminiowa głowica na gorąco się rozszerza i łatwo uszkodzić gwint. Naprawa gwintu kosztuje wielokrotnie więcej niż robocizna przy świecach, czyli PLN 160.

How much does it cost to replace glow plugs in a diesel?

Diesel nie ma świec zapłonowych, tylko żarowe, które pomagają przy rozruchu. Według nielicznych cenników wymiana jednej świecy żarowej kosztuje około PLN 105, a komplet w czterocylindrowym silniku około PLN 500.

Translation of the original Polish article dated 30 September 2026. Quotations from price lists are in Polish, as published by the companies. Read the original in Polish.

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