Replace 4 NGK iridium plugs on a boxer engine — labor-intensive due to access.
Reviewed by SubaruReview Editorial Team · Last reviewed 2026-05-15 · Editorial standards
How this repair stacks up against the other common Subaru maintenance jobs — useful when you're sequencing what to fix first.
| Repair | Cost range | Labor | Parts | DIY |
|---|---|---|---|---|
| Subaru Spark Plug Replacement Cost (Boxer) (this page) | $250–$500 | 2–2 hrs | $40–$100 | 3/5 |
| Subaru Timing Belt Service Cost | $700–$1,400 | 4–6 hrs | $250–$450 | 3/5 |
| Subaru Front & Rear Differential Fluid Change Cost | $180–$380 | 1–1.5 hrs | $60–$120 | 2/5 |
| Subaru Spark Plug Replacement Cost (Boxer Engine) | $240–$650 | 1.5–3.5 hrs | $60–$120 | 4/5 |
This repair is part of our Subaru repair-cost database and complements the reliability & common problems hub. Cross-check the underlying failure before you book the job.
Boxer spark plugs sit horizontally between engine and frame rails — labor is the cost.
Misfires, fuel-economy loss, fouled cats if delayed past 60k.
Expect $250–$500 at most US shops, parts plus labor.
2–2 labor hours typically.
Yes — DIY difficulty 3/5.
Misfires, fuel-economy loss, fouled cats if delayed past 60k.
Cost, labor-hour, and parts-price ranges on this page are aggregated national-average estimates. Individual figures are not tied to a single primary source and should be treated as directional — request a written quote from a Subaru dealer or an independent Subaru specialist before booking work. See our editorial standards for how we build these ranges.
No primary source is currently cited for the specific figures on this page. Treat quantitative details as directional pending verification — see our Corrections Policy to help us update it.
Independent Subaru specialists usually come in $300–$1,000 below dealer pricing on the $250–$500 range shown above, without giving up OEM parts. See real quote breakdowns in the Subaru repair-costs hub.
The most common trigger is AC Compressor Failure, documented with symptoms, root cause, and a permanent-fix path. Fixing the underlying failure first is what stops you from paying for this job twice.
Bundling maintenance work at one visit almost always beats paying labor twice. Owners on this platform also price out Subaru Timing Belt Service Cost and Subaru Front & Rear Differential Fluid Change Cost at the same appointment.
Yes — we rate it 3/5. Follow the job-steps checklist above and the money-saving tips, and cross-check the reliability hub for related failures worth inspecting while you're in there.
It's tracked inside our Engine Guides cluster alongside every related failure and fix. Browse all topic hubs to see repair cost in the context of the underlying engine or drivetrain issue.
Dig into the Problems Database to plan your next maintenance sprint, or browse every model hub for buyer's guides, generation breakdowns, and known-issue lists.