I know I'm reviving a really old thread but I promise it's for good reason!For context, I bought an '05 base model at around 194.5k miles at the end of 2023, and it still has less than 200k miles on it (it's my lunchmobile for the most part).

At the time, the owner didn't know when valve gaskets/spark plugs were changed and assumed it was the originals (owner had gotten car from her uncle, the original owner), and I had a, "if it ain't broke don't fix it mentality"

With higher gas prices and my mother in law stuck on the road in a DIFFERENT car due to not changing spark plugs, I was musing about changing them even though my car has no codes. Figure with high gas prices it couldn't hurt.

This thread scared me into thinking changing them myself could turn a straight-forward 2hr or so job into a nightmare, so I got a quote from an independent mechanic who...warned I'd be charged more if other things break essentially. But the base price is $411 for just the plugs to be changed ($300 labor plus $111 parts, the latter I think I could get for cheaper).

Anyone change plugs themselves have a recommendation of what to do here now that it's mid-2026 (leave it be, change myself, find a mechanic)? I have also heard the longer you do not change them the tougher they may be to change. Really I'd be willing to pony up the $411 eventually, but don't want this to lead into more issues where none exist.

Thanks!

 

I've done the job myself in both my LS400 and my LS430, its not that difficult. You will want a pencil magnet handy and take your time with all the connectors; things get brittle over time. If you are too nervous just spend the money and have a pro do it. The quote seems reasonable. The proper OEM plugs are very expensive and the quote you got seems right to me.

 

Thanks, but would you recommend changing them in my situation?

 

I think you should do it due to the age/milage even nothing is wrong with it at the moment.
If you don't want to deal with it yourself, have someone do it for you in a shop you trust.
If you want to save money and have the tools, you can DIY this job yourself. It's very straightforward. I would say less than an hour. (I did it on my 03 with 150K a couple years ago)
Only warning/suggestion is to use original parts from Lexus/Toyota (other members may disagree but that's how I do it for my Lexus/Toyota cars)

 

I agree with everything intermec says. If you have a shop do it, ask them if you supplied the plugs (purchased from a source like Lexus Parts Now or a dealer) would they just charge labor. You do not want them using likely counterfeits from the local parts store

 

You are right to think about what the mechanic told you if other things break and would be charged more. There are a lot of things that are brittle now and very easy to break plus breaking spark plug off in head is a possibility. Also used mainly for lunch how many miles would you do/yr. Tough decision to be pro active when it works and facing things breaking when being pro active. Also what is your gas mileage now on highway and city. If your mileage is not what others are getting it might would make your decision easier.

 

I'm getting 15mpg city and drive 2k miles/year. Basically was thinking this is something I do once for the "rest" of the life of the vehicle. Totally willing to pay the $411. Totally unwilling to risk a cascade of secondary issues in the attempt

 

What’s your biggest fear?
The electrical connectors on each coil is really the only vulnerable part. You should be able to remove the coils without disconnecting the wiring.
Changing the spark plugs on a 430 is approx. as difficult as changing the oil. Would you pay $400 for an oil change..?

 

Looks like a bunch more connectors and hoses to disconnect, which if brittle I'm concerned could break and then I'll have to order those and i turns into a far bigger time sink since I don't have those handy vs. a mechanic (I assume they have quicker access to things like hoses?)
Also, I change my oil without power tools (a vid had a torque display) which seem more needed to access the coils (which I'm also told I should be careful around).
So not sure what the "worst case" parts/labor cost would be if I break every connecto and hose along the way lol

 

If the plugs are original and in there for 20 + years they might possibly take more effort and skill to remove - one more reason to hire a pro because if you break off the top of the plug (e.g., from an ill-fitting socket or too much torque) you are screwed.

 

In 2026, I don't feel the quote you got is that high, that's not even 2 hours labor. BUT, yes, I would DIY to avoid the cost. Also, if a dealer, they routinely change 7/8 plugs and avoid doing the one by the dipstick from what I read.

Even if it were serviced by the book, you would have 40k to go before they would get changed again. imho if it ain't broke don't fix it doesn't apply to plugs, you don't want to chase misfires as a result. Just DIY or pay the $400, either way isn't the end of the world. Or if you're not keeping the vehicle don't bother. Conventional wisdom says to replace.

 

Yeah this is exactly what I've heard, ha. A VERY good chance they are the originals.
So then it becomes a question of whether to leave them be since I only drive 2k miles a year and hope for the best or risk someone I don't know messing something else up.

 

Don't change them just to get better gas mileage. 15 in City is pretty typical even with brand new plugs. At 195K miles, if they are original, they really should be changed by now and the risk of anything being messed up are low if you have a pro do it. They were due for change about 100,000 miles ago.