Skip to main content

Lexus IS250 GS300 carbon build-up - What you need to know

If you own a Lexus IS250 or GS300, your engine may have a carbon build-up issue. Here is what to do and why you should not worry.


The Lexus IS250 and GS300 sedans use small V6 engines with very high compression. Due to the nature of their design they are subject to a build-up of carbon inside the parts of the engine surrounding the combustion area. Valves and other components can become coated with this carbon and then the engine will run roughly at idle, or possibly even stall. If you have an IS250 or GS300 and these issues have come up you should take action, but hold off any panic. Lexus is trying hard to take care of customers with this problem.

Lexus IS250 GS300 Customer Support Program
The first thing to know is that Lexus issued a letter to all 2006-2010 IS250 and GS300 owners explaining the issue. The letter also offers help. Although not a recall, Lexus is offering to correct the problem and has added a 9-year, unlimited mileage warranty on affected cars. If somehow your vehicle falls outside the coverage a bit try speaking to your dealer. They are likely to help. If not, try keeping the discourse civil and contacting Lexus regional customer service for help. They may intervene and offer to pay for some or all of the work the dealer needs to do to correct the issue. Lexus created the coverage plan to capture all of the affected cars. Newer cars might still be under the car’s drivetrain warranty anyway, and there were not many cars affected older than 9 years when the program was started.

Carbon Buildup – The Fix
Lexus will remove parts of the engine and try to remove the carbon. Failing that, parts will be replaced. Some owners report “my engine was replaced.” Lexus is not fooling around. They are making the engines right.

Carbon Build-up – How to Prevent It
The most important thing to do is always to use name-brand premium fuel. This ensures that your engine is receiving the most detergent possible. Fans and owners also say that driving the car hard (redlining the engine occasionally) also helps. Others say it is not possible to prevent the issue, but redlining one's car is also good for the soul, so why not?

Have Your IS250 or GS300 Inspected
If your IS250 or GS300 is getting close to 9-years old, it might be wise to take it to a Lexus dealer for them to inspect the car for the issue. Even if you are charged, which is unlikely, you will either receive needed repairs, or you create a paper trail for future help if needed.

Photo courtesy of Ryan Nanyets, Lexus IS250 Owner and Facebook Lexus IS Owners Club Contributor


Ronnie Buck (not verified)    November 11, 2016 - 8:10AM

In reply to by Shawn (not verified)

As of 11-6-16 my IS250 with 75k miles in shop with same issue, 9 year warranty out of date by 5 months. Lexus has agreed to pay $1500 toward 6k rebuild

I'm still in negotiations but after reading blog realize I'm not going to get anywhere. I would like to stay in contact and pursue Class Action Lawsuit

Shawn (not verified)    November 11, 2016 - 11:06AM

In reply to by Ronnie Buck (not verified)

After extensive complaining and calling various people at Lexus 800 number then being forwarded to Lexus corporate - of which I am still waiting call backs, that I will never get...... Lexus basically told me to get lost / they would not do anything beyond covering parts.

Being in was not going to put 5-7K in my car I asked if they would do the top engine cleaning described in the other posts.... after a week they agreed. (Service Advisor told me they were more then willing to do this as it was cheaper / only cost them $200ish dollars - retail $600ish)

My car now runs better then it ever has! Granted, I know it's just a band-aid and the issue will occur again in most likely 4-6 years.

I am still searching for a class action attorney who will handle car cases.... because a bandaid is not a proper fix in my opinion! I will keep you and everyone posted.

Eva (not verified)    February 2, 2017 - 7:11PM

In reply to by Ronnie Buck (not verified)

My IS250 with 100k was in the shop for a month...having the same issue, with oil consumption and misfire. I had two(2) oil consumption tests when it was still under warranty, but the misfire happened 1 month after the warranty expired and now they will not fix it. The only fix they did was a top engine cleaning, which is not going to fix the issue, if just makes it go away until the carbon builds up again. I would like to stay in contact and pursue a Class Action Lawsuit myself.

Shawn (not verified)    October 17, 2016 - 1:58PM

2006 IS250 --- 1st Owner
Purchase in June 2006

My car is in impeccable condition, both inside & out... near like new. Always & 100% current on all services. Any and everything the dealer says needs to be done, we get it done.
Since roughly year 2, the car started rough idling and I immediately reached out to the dealer inquiring. Dealer asked about dash lights which came on then off after a couple minutes. Dealer said with no lights, to just monitor & they would check upon next service.
Same story till current day. Sometimes the dealer could not duplicate the issue & sometimes they could but said without a check engine light, they had no way to diagnose.
Took the car in for its 120K service in late August 2016... and was given a "clean bill of health". The very next day, the rough idling started more frequently. Reached out to the dealer since the lights go off, they said just monitor. 2 1/2 weeks later on a Sunday, driving down the freeway, I attempted to accelerate and the car chugs & basically loses all power... Dash lights up like a Christmas Tree. Pull over as safely as I could & turn the car off. After 15 minutes of trying, the car finally restarts and works... but the dash lights remain on. Called dealer on Monday & got an appointment for Wednesday. The following Friday, dealer calls me with diagnosis of misfire / carbon build up & $7 - 10K estimate. She then shared the issue is a known issue and she reached out to her regional Lexus rep for repair assistance.
(I Google said issue & come across this blog / posting to find its a common issue & Lexus is taking care of the problem) Service rep calls me last Wednesday to inform me Lexus rep agreed to cover the cost of retail parts ($2500) but labor is not included ($6000 = $160 hour = 39 hours). I asked what's next & she referred me to open a case with Lexus Corporate. I did so, the call center rep said the issue is a known issue & Lexus gave a 9 year extended warranty. With the initial 4 year + 9... I said cool, I'm covered. Rep informed me it was / is 9 years from when the dealer put the car into service... so I am just outside of the warranty. She then said not to worry because Lexus stand behind its cars and she was sure everything would be taken care of. I then call dealer service rep to inquire why over the years was my car never fixed after the many times I reported the rough idling / all the symptoms the issue cause & service rep said "even though we could duplicate the issue, without a check engine light & code, Lexus would not have agreed to fix anything until we were able to hook the car up, upload the codes & duplicate the issue."
Case manager called me this past Friday to inform me, since the dealer is covering $4000 in parts, and the car is out of warranty, they will not be doing anything else. I then shared why was I never informed about the "warranty" or engine issue & why was my car never fixed the many times I reported it... and she basically concurred what Service Rep told me. I then informed her the Dealer is not covering / has not agreed to cover anything yet and it's the Lexus rep who agreed to cover all parts @ retail value of $2500 so where did she get the sum of $4000... to which she had no answer.

I then reached out to several Class Action Lawsuit attorneys whom should be calling me back today.

All the above said, I'm going to the dealer this morning to speak with management to see what's up. I doubt by reading all the comments above I will get anywhere.

What good is a "warranty" if A. The consumer does not know about it and B. If the warranty is only "valid" / the manufacturer will only act upon the warranty IF the check engine light is on when tested???

We spent $40-55K for these cars and the issue was known immediately -- thus Lexus should have recalled them & fixed the issue.... not wait 7,8,9 or 10 years until the repair cost is basically the same cost of the cars value!

Anyone interested in a class action suit? Please send me a note if you are and or if yoy were able to make any headway with your dealer / Lexus corporate.
[email protected]

Dee Pumy (not verified)    November 24, 2016 - 11:38AM

How can we file/be part of a class action lawsuit against Lexus for the cbu issue? There are just entirely too many of us owners that are experiencing this problem.

Dave (not verified)    December 17, 2016 - 2:07PM

Bought a used 2006 GS 350 in 2013 and was not informed of any problems. When we complained to a dealer (different location, same ownership), in January 2016 about rough idle and warning light coming on and off, they replaced the computer, at a cost of about $3,000 to us, and sent us on our way, with no warning that catastrophic engine failure was possible, to the tune of $11,000 to repair, at a minimum, and as much as $4000 more. Had Lexus told us of the problem, we would have traded it to them on a certified used car - yes, I understand the ethics of kicking the can down the road so it becomes some else's problem. As it stands, they will offer us $2000 for the car, plus forgive the $800 in labor they say they have incurred in getting a diagnosis that went from $6,000 to $9,000 estimate, to $11,000, to, well maybe $15,000. We are not directly out of pocket a great deal of money, since the car has a wholesale value of $5,000-$6,000 and we might have been able to get $8K to 10K if we sold it ourselves, but we have lost the utility value that a Lexus, by reputation, should have beyond the 150K we had on the car.

What bothers me more is the dealership that is quoting the repair costs has disingenuously stated the the problem become known only recently. It was known when they sold us the car, when they serviced the car, and when they replaced the computer, but they mentioned it not once.

Lisa (not verified)    December 17, 2016 - 8:13PM

Same situation here. 2006 IS250, outside the 9 year window. Been complaining about the issue for a while now but without the lights and codes, they said they couldn't do anything. My lights are on all the time now and it's idling rough. I feel like this issue happens right outside the window for the fixes. Kinda like it's planned that way? Who knows. I'm just so frustrated because I don't want to drive this car without a fix, Lexus won't pay for it, and my dealer says it's a $12-$14,000 fix out of pocket! Any new developments out there??

Shawn (not verified)    December 18, 2016 - 8:56AM

Greetings Fellow Lexus owners...

I am pursuing a class action suit with a couple of large law firms. Once one agrees to take on the case I will notify / update this post.

Steven Smith (not verified)    December 30, 2016 - 4:25AM

In reply to by Shawn (not verified)

That's great news please inform. I'm waiting to pick up my 07 is250. I took it in for an inspection and the dealer is telling that the water pump needs to be replaced and my front bumper needs to be replaced those two things costing 4000 insane if u ask me he also said since we are doing all this they will do a top engine cleane and replace my spark plugs costing me 700 Lexus is trying to tell me that originally it's 1800 but since I'm spending 4000 they will do it for 700 how does this sound? Are they trying to get over?

Thanh (Tomi) Nguyen (not verified)    December 20, 2016 - 12:31AM

My name is Thanh Nguyen. I just recently purchased a 2006 GS300. Before purchasing the car, I double check the vin number with carafe and also called Lexus with the vin number to see if any of the recalls were done. There were a total of 9 recall. The car had only 115k miles on it. Any and all services were done by a Lexus dealership, with a total of 50 services. I only had the car for one day and my check engine lights came on with a VSC warning. I took it to an auto parts store to scan the code and they said there was a carbon build up and that I had to replace the catalytic converter. The car would idle high every once in a while. Can you let me know if this is what everyone was referring about when they said there was carbon build up? Am I able to also get involve with a class action lawsuit since I did talk to Lexus about any recalls done and any future problems? Please let me know. Thanks

Vinny (not verified)    December 28, 2016 - 9:53PM

Hi guys!!! I need some serious adevice on what is the next best course of action that I should take, neither against the dealer or lexus Corp. My car is out of warranty and the diagnosis said I'm quality for the fix, since it's out of warranty, lexus only will pay for half of the $9400 dealer quoted. In my depends, I never got the CSP letter, lexus service advisors never disclose the known oil consumption problems. My car is 2006 and it only has 72k on it now, oil construction started at 60ish K.....anyhow, I just want some real feed back from the lexus community experts so I can move on from this BS headache....thanks in advance


ronna smath (not verified)    January 3, 2017 - 2:58PM

having the same carbon issue brought it to lexus when I was under warranty and they lied and said I needed a tune up and they could not get the car to do what I said was happening with sudden decleration
I did the tune up 6 mos later starts acting up again and now they tell me im no longer under warranty and want to charge me for repair-its a waste talking to anyone because they all have the same answers

VR (not verified)    January 7, 2017 - 10:35PM

I have a 08 IS250 with 100,000 and have had no issues with rough running but am worried as my nine year window is fast approaching. Are all cars with this engine affected or are some cars never going to have the carbon build up problem? Also, if engines are being replaced, is a replacement with a 350 motor an option or does the type of transmission negate this option? Are new re-manufactured 250 engines a potential solution if out of the warranty window? I love the car and want to keep it for another eight or so years.

Honesty Counts (not verified)    February 10, 2017 - 2:59AM

I don't think anyone here at this forum really understands what the heck is going on in their engines: IT HAS NOTHING TO DO WITH THE GASOLINE !!! It is oil vapors coming from the crankshaft via the Positive Crankcase Ventilation system that is causing all of these problems. You have to STOP the oil vapors from flowing from the crankcase to the intake valves, it is as simple as that. Find out what hoses go from the crankcase to the intake duct-work / tract, removed them from the air intake, and plug the holes in the air intake that are left behind. If you don't plug the holes in the intake then you get a massive vacuum leak and your car won't run right. The hoses that come off from the crankcase: just leave them open so the vapors from the crankcase are vented into the atmosphere. if too much oil vapor is making an oily mess of your engine bay then add a longer length of hose so that the oil vapor is exhausted down near the bottom of your engine, so it flows onto the ground under the car. Just remember to re-connect everything back to the normal way it was for your annual emissions test, that's all. If you do this then the oil vapors from the crankcase won't deposit themselves onto the hot intake valves, its as simple as that.
Using gasoline with additives won't stop oil from depositing itself onto valves unless the car has PORT INJECTION on it. If the car has PORT INJECTION then the additives in the fuel will help clean the intake valves because the spray of fuel is blasted directly ONTO THE VALVES themselves, cleaning them with the spray. But in a pure direct injection car there is none of this spray of gasoline onto the valves so additives in the gasoline or the quality of the gasoline has ZERO EFFECT.

Shawn (not verified)    February 10, 2017 - 12:46PM

In reply to by Honesty Counts (not verified)

Lexus is 100% aware the engine they chose to use for the IS250 & GS300 years 2006 - 2012 has this issue.
Regardless of cause, Lexus has determined the only way to properly repair is basically replacing many components of the engine & all pistons... at a total cost of $7-10K.

Only challenge now is to see if there is a viable class action case being many owners have been and are starting to run into major problems due to the faulty engine.

pat (not verified)    July 6, 2020 - 10:10PM

In reply to by Honesty Counts (not verified)

you are correct about better quality fuel impacting this issue. Direct engine engines means the fuel injector spits fuel directly into the cylander so it cannot bathe and clean the carbonized area

Krystal (not verified)    March 3, 2017 - 2:26PM

I had the same issue with the rough idle even after replacing spark plugs Exedra so I looked up the letter for the 9 year warranty unlimited mileage I contacted my local dealership and they are now replacing all the Pistons gaskets plugs excetera and it's all on Lexus is dying if you're having this issue I would suggest contacting your local dealership and having them honor the warranty for the carbon buildup

Tim (not verified)    March 27, 2017 - 5:52PM

I am having the same problem with only 58k miles. I bought this car used 1.5 yrs ago with only 29k miles. It was bought from a Toyota used car dealership. Of course no one informed me about the engine warranty plan that expired 5 months ago nor that the engine had issues. I am getting no where with Lexus . Any info on a class action suit ? Please advise. [email protected]

Brad (not verified)    April 5, 2017 - 10:49AM

Same issue for me. Fed up with Lexus! This is a quality brand? I've had Fords last longer. My 2007 IS250 had warning lights come on and has 2 cylinders misfiring. Dealer confirmed the carbon buildup issue. Lexus is denying the repair since it is over the 9 year warranty. They only offered $1500 towards the $6000 repair. Car only has 85k miles and well maintained with only premium fuel. We are paying for a bad design. If they don't make this right I will never buy a Lexus again and convince others to do the same. They will lose more than $6k from this.

Shawn (not verified)    April 6, 2017 - 6:07PM

Fellow IS250 & GS300-50 owners...
I've got bad news -----
I recently spoke with a very reputable & well known lawyer & law firm out of Los Angeles, who has successfully taken cases and won & currently has a couple cases, against various large auto manufacturers. He looked at our thread / this page and a couple others on the web pertaining to the carbon build up issue prior to reaching out to me for out appointment. He also had me obtain a copy of the " 9 yr Bulletin" Lexus issued for said issue so he could view the wording, etc.
He shared, that although there is clearly a manufacture / product defect, in the court of law and how the laws are written, when interpreted by every judge he has had a case against for various defects & issues, should a new car / truck properly function for 4 to 5 years max from the date it is purchased, the car / truck "lasted" / did it's job and the auto maker rarely is or can be held responsible.
So, he said that although there is clearly a defect, and it sucks Lexus is not standing by its cars, being the full issue, pistons failing, misfiring, build up and challenges etc., does not occur in most cases until the 9 year mark / Bulletin time frame, we do not have a case or in his words, one he feels comfortable taking because he knows it would be a losing battle.

The above said.... for my situation & car, instead of dropping a dime to "repair" the issue, even though Lexus "offered" to cover the parts ($1800-2500)... I requested they cover the top engine cleaning (retail cost $300-600). Lexus agreed and honestly, my car has never ran smoother.

Yes, it is a Band-Aid and eventually (probably 3-5 years) the issue will come back AND I didn't plan on buying a new car for another couple of years.... the top engine cleaning works(ed), allowed me to clear all the check engine lights etc, and when I find the next car I want to buy.... I can & will still get full KBB trade in or private sale value.

If you haven't done so... I would recommended you do the same. Sorry I struck out!

michael Dreebin (not verified)    March 15, 2021 - 4:27PM

To all you concerned folk:
-My 2006 is250 top part of engine was completely replaced(free- courtesy of Lexus Carlsbad) in 2016 due to the voluntary recall
-25K miles later in 2020 the carbon build up returned on cylinder #3(along with all relevant dash lights) where an engine flush was recommended/clean #3. = $900 paid by me
- 2K miles driven and 6 months later, exact same dash lights/symptoms occurred and dealer is now telling me "O well, needs a $6k engine teardown to determine scope of the issue and then most likely a new full long block engine". AT MY EXPENSE. Car is worth $4k.....haggling with Corporate currently-I'll be lucky if they keep it and give me 2K towards a trade-in..... SAD......Buyer beware