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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.
IS250 GS300 Lexus Carbon Build Up

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

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Comments

Mark Day (not verified)    June 4, 2015 - 2:44PM

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"The most important thing to do is always to use name-brand premium fuel." Since gasoline, and engine oil, formulations are unknown, it is impossible to determine which is superior or satisfactory – Walmart, Shell, or ExxonMobil.

John Goreham    June 4, 2015 - 5:26PM

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Excellent point. Also true is that there is a minimum detergent level required by law. However, some fuel suppliers voluntarily meet a higher standard for fuel, but the Premium grade is not necessarily superior. I liked this story by Motortrend on the subject: http://blogs.motortrend.com/1403_all_fuels_are_not_created_equal_technologue.html
Thanks for expanding the topic. Cheers,

Anthony (not verified)    June 25, 2015 - 7:18PM

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I'm having this problem for years now with my car, can you please email me a copy of this letter I can't find it anywhere online please it would be very helpful - Anthony

Liz (not verified)    October 23, 2017 - 5:50PM

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I did purchase my 2006 Lexus IS 250 from a dealer and she is burning lots of oil. I would like to deal with this problem ASAP. Kindly email me copy of above mentioned letter. Thank you very much!

Mishimoto San (not verified)    January 29, 2019 - 5:20PM

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Kumbawa. The problem affects all the Is250 of the second generation worldwide. The 3IS introduced a port+direct injected trouble-free version of the 2.5. This engine, whatever, on this version, isn't very popular and was quickly discontinued in the EU market.

David R (not verified)    October 28, 2015 - 8:46PM

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Just took my 2010 Is250 in for 3 recalls and they mentioned the known issue of the carbon build up causing engine to feel as if it will stall but they said my Vin wasn't under the covered list and it'd cost me 650$ for a top engine clean. My father in law is a mechanic and he said to try letting the tank go to E and refilling with Shell premium gasoline. He said this has fixed the issue with some of his customers. Worth a shot before spending that much money.

Mia (not verified)    October 29, 2015 - 3:11PM

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Thank you for your advice. Called Lexus Corporate and they only offered a top engine clean so I took their offer. Had the car in the shop for 3 days and just got it back yesterday. It shuttered twice since I've gotten it back, smh. But my car was returned to me on E, it was almost empty when i dropped it off, so being scared my car was going to die on the road i went to the nearest gas station (76) and pumped their 91. Im going to take your suggestion and wait til I'm on E again and pump Shell Premium. I've always pumped Shell but the 89 octane instead of the 91 (lesson learned I guess). I guess I'll also pump Chevron every now and then. Which gas is better though? Shell or Chevron?

Jim (not verified)    January 20, 2016 - 9:07PM

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Hello guys ! i am in market for a 2012-2013 is250s. Do the 12'-13' having this problem or just the 06-10 250's? Thanks

Vera Haubold-Dias (not verified)    August 25, 2016 - 6:50PM

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Hello Jim:

I am having issues related to carbon buildup with my Lexus IS250, year 2012, and would like to know if you have been able to find out more information about the 2012s?

AJ Thompson (not verified)    February 4, 2016 - 5:41PM

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Can someone please forward me the letter as well. I would like to check and see if my IS250 2007 is one of the affected VIN - under recall. I have a "slight shutter" at times during idle. However, I just purchased the car, and an aftermarket warranty, owned for about 3k miles, but I have always used premium...any suggestions?

John Goreham    February 5, 2016 - 10:44AM

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Hi AJ. I removed your e-mail to avoid possible spam. You can check your Lexus at this website very quickly to see if there are any open recalls: http://www.toyota.com/recall Just cut and paste that into your browser. Or, you can simply phone Lexus and ask them at : 1-800-255-3987 Your local dealer will also tell you by phone or in person. If you ask in advance, you might find that Lexus will do a no-charge evaluation, but check before hand to avoid surprises. Good luck.

Bruce (not verified)    September 5, 2016 - 1:49PM

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The notice went out to every buyer who purchased a 2007-2010 is250. If your car is experiencing a carbon build up issue, you don't need the notice/letter. What you will need is a mechanic to install a kit which is a three phase flush and change how the fuel is injected into the valves. Top end flushes are a temporary relief, it is not a fix. The flush, kit and labor are surprisingly inexpensive. $400-600.00.

Phillip (not verified)    April 5, 2016 - 2:02PM

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I bought a 2008 Lexus IS awd in August 2015 and within the 1st month had low oil enjgine light come on and almost like a rotten egg smell when I would hit top RPMs took it to kuni Lexus and they gave me the run around and said if it happen again or gets worse they will look in to it they said I was still under warranty of the carbon build up and of course 5 month later vsc code popped up and car completely stalled out on high way due to carbon build up took it back to kuni Lexus and they tell me car had already been serviced for the carbon build up and wasn't under warranty any more because it's already been serviced for that problem come to find out the way they fix this carbon build up problem is a top engine and piston clean but it's only a quick fix not a guarantee fix so after an up hill battle with Lexus car company and kuni Lexus dealership we came to a deal of me paying for maintance $3100 and Lexus paying for parts $7100 so a $10200 job they replaced short engine block and I payed for a new water pump and spark plugs since they already had my car opened up got the car back almost a month later and 2 month later still having problems again low engine light coming on and the smell is back no idea what to do but really disappointed in Lexus right now any infor or suggestions please help thanks

Bruce (not verified)    September 5, 2016 - 1:18PM

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There actually is a fix to the carbon build up. Your issues sound identical to mine with exception of the smell and low oil light. Those we have not experienced. The carbon build up is due to how the fuel on that particular motor passes through the valves. There is a kit that re-routes how the fuel is injected. It first has to undergo a chemical clean consisting of three different cans of solution. Ultimately these chemicals eliminate the carbon and glass like build up off the valves. The kit re-routes how the fuel is injected. Surprisingly, the mechanic charged only $400.00 for what exceeded six hours of work. I suspect that was a gift as they had done a top end cleaning 8,000 miles before. Lexus dealerships have since adopted this same procedure. As you experienced, Lexus is worthless kidding themselves and the customer regarding the carbon build up. If you want the name/supplier of the kit and technicalities, you can email me. [email protected]

Bruce Banner (not verified)    August 2, 2016 - 4:07AM

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All the comments about Lexus remedying the carbon build up is BS. I've had a 2009 motor rebuild and subsequently two dealer carbon flush. They have since kicked me to the curb. Telling me the issue can be prevented by using Chevron techtron 91. I even added a sea foam additive with every fill up. 3,000 miles later the car returns to its failed state. The motors from 2006 to early 2011 are losers and Lexus will hang you out to dry!

Candi Cavasos (not verified)    September 23, 2016 - 6:20PM

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I am disappointed too. Have a 2006 is250 biggest piece of crap. They charged me $500 for a tune-up because of all my stalling and hesitation problems then two months later they replaced my engine another tune-up everything was paid I still have a lot of problems. stalling. hesitation. smell of eggs my kids are worried to drive with me. I have 80000 miles on it because im afraid to drive it. I have called customer service. taken the car in multiple times now they're trying to tell me the only thing that's coding is the transmission. I cant afford to buy a new car. All i want is it fixed. It's sad when your afraid to go out of town because you don't trust your car

2006GS (not verified)    August 2, 2016 - 7:46PM

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They rejected my claim with the car just a few months outside the 10 year window. Under 80K on the clock then, too. I had the rough idle a couple times, and the dealer ran some engine codes and said I needed the full $7000 rebuild, and that Lexus was unlikely to cover it under the so-called CSP.
I kicked it up the corporate chain of customer service command a few notches and they just said no. I was 2 months outside the 10 year window from date of manufacture, mind you, not model year. So because my car was built August 2005, it didn't matter that it was 2006 model, in the year 2015 when I tried to get them to honor the CSP. I was infuriated. I can't wait until I can buy a new car, I'm going to take a picture of me and my Audi S7, and say "nice work Lexus. You pissed off a customer to save $6K and lost out on a $60K sale of a new luxury car.

Lexus does NOT care about customers who keep their cars a long time. They are all about leasing the latest flashy bauble to stupid people who don't have the cash to pay.

Nick (not verified)    September 8, 2016 - 9:53AM

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As a professional engineer, IS350 owner, and graduate of a combustion engine design program under an SAE Fellow, I really see this both ways... First, you're asking for a "free" $7k engine re-build on a 10-year old car. An insurance company would declare this a total loss if a collision resulted in as much damage. Do another $600 top-end clean on your dime, and use exclusively Top-Tier gas (Exxon, Chevron, Shell, Costco, Valero, BP, Conoco, just to name a few). These fuels use 2-5x the detergents of other gasolines and make ALL the difference in these DI (direct injection) engines. Boom - crisis averted.

Otherwise, yes, go ahead and "stick it to 'em".... and later learn Audi had WAY more problems implementing DI - the same tech causing your carbon issues - in their first incarnations of the technology, and with MUCH worse customer service... Enjoy!

Bruce (not verified)    September 8, 2016 - 4:20PM

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Mr. Engineer,

With your qualifications and a being a graduate of combustion engine design, how could you not know that the 250 and 350 motors are not one in the same? More to the point, the difference in the "design" and delivery of the fuel injection system of these motors. The grade of fuel is an unrelative and non issue respective to the cause and effect respective to the carbon build up surrounding the valves on the problematic 250 series. "Boom." You are fortunate to be driving a 350 otherwise, you to would be paying $600.00 for a top end cleaning every 7-10,000 miles had you chosen a 250. For those with a is250 year 2007-2011 there does in fact exist a fix.

Vera Haubold-Dias (not verified)    August 25, 2016 - 6:52PM

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Does anyone know why are the models 205is 2012 different, if they have the same motor as the previous ones?

Bruce (not verified)    September 5, 2016 - 1:28PM

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Lexus changed how the fuel injection enters the valves. The problematic motors started I believe in 2007 to early 2011. 2012 motors will be clear of the carbon build up issues.

Rhea (not verified)    July 13, 2020 - 12:26PM

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Negative. I have IS 250, 2012 having the same problem with the carbon buildup. Lexus says it needs top engine cleaning, remove plugs, intake/valve clean for $1164.65. NO DIFFERENCE IN ISSUES RESEARCHED FOR 2006-2011.

Shawn (not verified)    October 17, 2016 - 11:13AM

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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]