Help Needed: Possible Carbon Buildup 2008 IS250?

Brooks2IS · Oct 5, 2015

I've searched the good ole Internet high and low for a concise analysis of the issue my car is currently having and, though I speculate that my IS is suffering from the dreaded carbon build up issue, I have no direct answer. I'm hoping that you all can offer more insight.

Late this evening, on a normal drive home, my 2008 IS250 RWD w/ 104k threw on a CEL as well as the accompanying VSC and Traction Control lights. I immediately stopped by AutoZone and my car is reading error code P0420, Catalyst System Efficiency Below Threshold. CEL is not rapidly blinking, so I brought the car home.

Unfortunately the closest Lexus dealer is an hour away so I'll be taking her to the local Toyota dealer first thing tomorrow morning, but I need to go in well prepared. Are there any official TSB's on this issue? I've read yes and no on the internet, and I know that this is a common issue. What should I expect in terms of fixing the issue? How about cost?

I should mention that the car receives regularly scheduled maintenance, every 5k at the Lexus dealer, and always gets 93 octane.

Thanks in advance.

TripleL · Oct 11, 2015

I just saw this thread, how did you make out?

There is a TSB on the 06s and 07s,, I don't immediately recall if the 08s were part of it, but they could be.

I can tell you that the symptom for the recall is typically the car stumbles or idles rough momentarily at a traffic light or similar at random times. Has that been happening to you?

Brooks2IS · Oct 12, 2015

TripleL said:
I just saw this thread, how did you make out?

There is a TSB on the 06s and 07s,, I don't immediately recall if the 08s were part of it, but they could be.

I can tell you that the symptom for the recall is typically the car stumbles or idles rough momentarily at a traffic light or similar at random times. Has that been happening to you?

Ended up having to replace one of the two catalytic converters... Here we are $2200 later! Not a fun week last week. Worst part was no loaner car.... I forget how nice Lexus dealers are!!

My car still stumbles momentarily in traffic. Fingers crossed I don't get hit with carbon build up down the road.

IS-SV · Oct 13, 2015

Sorry to hear of repair needed.

Thanks for follow up report. Did mechanic mention if it's common?

Brooks2IS · Oct 13, 2015

IS-SV said:
Sorry to hear of repair needed.

Thanks for follow up report. Did mechanic mention if it's common?

The mechanic at the local Toyota dealer said that he doesn't see many Lexuses, period. I called my regular dealer, Butler Lexus, and my service advisor said that while the issue is not common, its not unheard of. She's seen a handful of these cars have this issue.

IS-SV · Oct 13, 2015

Recently I've only seen people replace cat converters on Toyota and Acura vehicles that were over 20 years old.

Your feedback/report is appreciated.

Brooks2IS · Oct 14, 2015

IS-SV said:
Recently I've only seen people replace cat converters on Toyota and Acura vehicles that were over 20 years old.

Your feedback/report is appreciated.

That's all I've seen as well-- I was shocked to see that I had to replace mine already.

Not a problem, I hope this thread is somewhat useful to others in the future.

TripleL · Oct 16, 2015

Brooks2IS said:
Ended up having to replace one of the two catalytic converters... Here we are $2200 later! Not a fun week last week. Worst part was no loaner car.... I forget how nice Lexus dealers are!!

My car still stumbles momentarily in traffic. Fingers crossed I don't get hit with carbon build up down the road.

Sorry you had that repair although your symptoms did sound different than the carbon build up ones. Hopefully your good now for another 104K miles!!

corradoMR2 · Oct 19, 2015

Not to undermine the issue, but you have 104k miles on the car? Is this the first major "break/fix" repair on the car? I think that's pretty decent and you shouldn't feel too bad. Glad it's up and running.

Brooks2IS · Oct 19, 2015

corradoMR2 said:
Not to undermine the issue, but you have 104k miles on the car? Is this the first major "break/fix" repair on the car? I think that's pretty decent and you shouldn't feel too bad. Glad it's up and running.

Unfortunately, it's not the first issue, but it is the first major issue. I had a water pump go out at 78k ($900) and replaced each HID on separate occasions ($500 total). I should realize that the car is nearing a decade in age so things are bound to happen, but still... This year has been back to back expenses, the 90k service, catalytic converter, new tires... all the joys of car ownership, I guess! Still more reliable than a German!

IS-SV · Oct 19, 2015

Great long-term ownership report Brooks21s, helpful to those with older gen2 IS's.

My 2007 IS350 has about half that mileage, but you've provided some things to watch for (water pump, HID for example seem to happen to 250's and 350's). I'm still waiting for my original battery to die. I did have a brake light switch go a couple of years ago, cost about $125.

fyi - I put 128K miles on a Mercedes 2008 C300 recently. Other than $450 for tensioner/belt/pulley replacement, no other out of warranty repairs. Still had original battery and wipers at end of ownership, brake pads replaced only once. I used a independent Mercedes tech/shop consistently.

IS-SV · Dec 1, 2015

IS-SV said:
My 2007 IS350 has about half that mileage, but you've provided some things to watch for (water pump, HID for example seem to happen to 250's and 350's). I'm still waiting for my original battery to die. I did have a brake light switch go a couple of years ago, cost about $125.
.

Update - Nov. 2015:
Replaced battery with another Lexus battery since this one was at least 8 1/2 years old, about $200. (Although battery tested okay in the summer at last oil change, it was cranking a bit slower by fall so I replaced it before problems developed.)