Replacing all six spark plugs in a BMW 335i generally costs about $250–$600 at an independent shop, with dealership pricing often higher. If you do it yourself, parts costs typically run about $60–$180.
What determines the price
Engine type and plug technology
The BMW 335i uses a six-cylinder turbocharged inline engine (variants include the N54 and N55). Spark plugs for these engines are typically iridium or platinum in modern replacements, rather than older copper plugs. Using OEM-grade iridium or platinum plugs tends to be more expensive but lasts longer, reducing future maintenance needs. Expect six plugs to cost roughly $60–$180 depending on brand and whether you buy OEM-equivalent parts or aftermarket equivalents.
Labor costs and accessibility
Labor is often the bigger component of price. The coil-on-plug design means workers must access each cylinder, which can take about 1.5–2.5 hours on most 335i models, though some configurations or garages may take longer if a coil or related components are challenging to access. In the United States, independent shops commonly bill around $100–$150 per hour for basic maintenance, yielding roughly $150–$375 in labor. Dealerships typically charge more, with labor often in the $200–$450 range depending on location and whether diagnostic time is included.
These figures break down into three primary components: parts, labor, and optional extras.
- Parts (spark plugs): Six plugs, cost varies by type and brand; budget aftermarket plugs can run about $60–$120 for six, while premium iridium/platinum OEM-equivalent plugs can be $120–$180 for six.
- Labor: Time to complete the job is roughly 1.5–2.5 hours; labor rates commonly fall in the $100–$150 per hour range in the U.S., amounting to about $150–$375 in labor.
- Optional extras (ignition coils, gaskets, etc.): If you replace ignition coils (often recommended if they show wear), coils can add roughly $240–$360 for six coils plus additional labor, depending on parts and shop rates.
In summary, the total cost is driven by plug type, labor rate, and whether you include ignition coils or other related components in the service.
Typical price ranges by service level
Here are common total-cost scenarios you might encounter, depending on who does the work and what’s included.
- DIY (parts only): Approximately $60–$180 for six plugs, plus whatever tools you already own. No labor charges, but you invest time and ensure you follow proper torque specs.
- Independent shop (most common): Roughly $250–$600 total. This includes six plugs and labor; price depends on plug brand and labor time. Optional coil replacement adds cost.
- Dealership: Approximately $450–$900 total. Higher parts and labor rates are typical, with OEM parts and diagnostic time often included in the quote.
When budgeting, ask for a written quote that separates parts and labor, and clarify whether ignition coils or any gaskets are included or recommended as part of the service.
What to ask your shop
Getting a precise quote
To avoid surprises, request quotes that detail: the exact part number and brand for the plugs, whether OEM or aftermarket parts are used, the number of ignition coils replaced (if any), the labor hours estimated, and whether taxes and disposal fees are included. It can also help to ask whether the price assumes you bring your own parts or if the shop provides them, and whether a diagnostic check is included if a misfire is suspected.
Summary
For a BMW 335i, replacing all six spark plugs typically costs about $250–$600 at an independent shop, with dealer pricing often higher. DIY parts-only cost is usually $60–$180. The biggest drivers are the spark plug type (copper vs iridium/platinum), the local labor rate, and whether you include ignition coils or other related components in the service. Always obtain a written, itemized quote and consider replacing coils only if needed or if wear is evident.