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Hi all, my gs450h has a blowing centre section exhaust, i assume its the original. The car has done 327k miles, yes you read that right. Occasionally the EML comes on, with error code p0420, 

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P0420 LEXUS Catalyst System Efficiency Below Threshold Bank 1

I can clear it, but it does come back after a few days, the problem is no doubt related to the blowing. Can these be got as used parts? Im struggling to find one. Do these have just the one CAT, or two?

cheers all!

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The exhaust Manifolds have one cat on either side. Then the centre section also has a cat in either pipe before they join, and enter the first silencer box making 4 cats in total. 

You will probably find having yours repaired or replacing it with a purpose made stainless steel replacement to be the cheapest options.

John.

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Thanks for the info. Is the attached pic the 'centre section' on a gs450h? Sorry for sounding ignorant, but the section looks different from underneath the car, viewed from a tight angle, as opposed to this. The code i get states its 'bank 1' catalytic converter issue, which CAT would that be here? Cheers

exhaust.jpg

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Yes that is the centre section. Bank 1 is the drivers side or the left hand side branch in your picture above as I believe the exhaust is turned over "upside down". I doubt the split at the rear of the resonator is the reason for that code.

John.

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I had a used centre section fitted today. Quiet as a whisper now. Bloody hard to track down that part, worked out £280 fitted. Or i could have gone for stainless steel at £600 plus i would have had to travel.

As it is all now silent, i assume i will not be seeing that code again!

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Good result, glad you got sorted. Did you get the part from a breakers?

 

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Were the two sensors supplied with the replacement exhaust? As it was one of these that was more likely to be causing the fault code.

John.

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On ‎29‎/‎08‎/‎2017 at 4:11 PM, carnut1980 said:

Thanks for the info. Is the attached pic the 'centre section' on a gs450h? Sorry for sounding ignorant, but the section looks different from underneath the car, viewed from a tight angle, as opposed to this. The code i get states its 'bank 1' catalytic converter issue, which CAT would that be here? Cheers

exhaust.jpg

That looks quite similar, if not the same, as the IS250 centre section

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Hiya yall, yeh from a breaker on ebay, yeah the two sensors came with it. Fitted by ATS euromaster, i wouldn't dare go anywhere near halfords, and i have heard some bad stories about kwikfit (tyre salesmen, nothing more). All sorted, but i do have a clunking coming from my front brakes, can you guys have a look at my latest post regarding this? I added a video with the noise! cheers

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