2004–2007 Buick Rainier
By Tom Becker ✓ Certified Mechanic · Published Sep 21, 2026 · Updated Oct 22, 2026
Save $335 by doing it yourself! Shop cost: $450
Quick answer: Spark Plug Replacement on a 2004–2007 Buick Rainier is rated Advanced and takes about 1-3 hours. You'll need 4 tools for this job, and parts cost about $115. This guide walks you through the full job step by step, including the mistakes to avoid.
| Part Name | Part Number | Price | Buy |
|---|---|---|---|
| Correct spark plug set for the gasoline/ICE engine in 2004-2007 Buick Rainier; verify engine, heat range, gap, and VIN fitment | — | $115.00 | |
| Coil-boot seals or ignition coils only if inspection finds damage Optional | — | $35.00 |
About prices: shown prices are typical retail averages and change frequently; cheaper alternatives may be available. Confirm the current price before buying.
💡 Pro tip: Order all parts at once to save on shipping
Follow these steps carefully
Confirm the 4.2L inline-six (LL8): ACDelco 41-103 iridium, pre-gapped ~0.043" — don't touch the gap, the tip is fragile. Buy six. The 5.3L V8 uses a different plug. Scan for misfire codes first.
Let the 4.2L cool fully. Pop the cover off, and disconnect the negative battery cable only if your service procedure calls for it. Unplug each coil's connector as you work down the row; the harness has enough slack.
Unplug each coil connector and remove the coil hold-down bolt, then pull each coil straight up out of its well. Keep the coils in order by cylinder. The inline-six's coils rarely fail, but check each boot for carbon tracking while it's out.
Remove plugs with a 16mm (5/8") socket, one cylinder at a time. Compare reach; check for oil fouling at the tube seals. Hand-start new plugs; tighten to the manual's spec — never use an impact. Cylinders number from the front.
Apply dielectric grease inside each coil boot, reseat the coils on their original cylinders, snug the hold-down bolts, and reconnect every connector until it clicks. Confirm a smooth idle with no check-engine light and take it for a drive to verify steady power.
I've learned this the hard way: Don't touch the gap on those 41-103s — the iridium tip is fragile, and the factory pre-gap around 0.043" is right. A code on the 4.2L usually means a worn plug, since these coils rarely fail.
Test your repair before closing everything up. If something doesn't work right, double-check your steps.
⚠️ Common Mistakes to Avoid
Acura CL · 2001–2003
Acura ILX · 2013–2022
Acura Integra · 2023–2026
Acura MDX · 2017–2021
Acura RDX · 2019–2024
Acura RL · 2005–2012
Acura TLX · 2015–2020
Acura TSX · 2004–2008
