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Aftermarket Stainless Exhaust system throwing Fault Codes?

T

TTW

Trainee
Joined
28 Jun 2014
Messages
79
Hi,

I recently purchased a replacement Stainless Steel exhaust system from Design911 for my Porsche 997.1.

The system contained replacement CATs and boxes and cost just over £1.5K

Having received the items promptly, and getting them fitted at my usual garage (along with all four lambda probes at the time of fitting the new system, as the existing ones would not free from the legacy system) - Everything was fine for the first 300-400miles, then suddenly the engine fault light was triggered, and following diagnosis the below fault codes were returned:

P0420: Bank 1 Catalytic converter system insufficient effect

and

P0430: Bank 2 Catalytic converter system insufficient effect

After clearing the codes, the engine light went off, and I assumed the issue was resolved however after a further 170miles, the same has happened again?

As the fault codes are relative to catalyst efficiency, and consistent across both independent banks, and as I have not experienced any fault with the vehicle prior to the replacement exhaust (and all four lambda probes at the time of fitting the new system) I can only assume the reason for the engine malfunction warning lamp and the faults stored is down to the exhaust system?

Have any you guys experienced similar or can provide some advise on how to fix this issue?

Thanks in advance
T
 
Were these 200 cell cats or less ?

The fault code is as it says .. the cats are not efficient enough .. it takes several drive cycles for the car to register this hence the miles till you get an eml light on .

Its also save the planet stuff and has nothing to do with the running of the car .

I would make sure there is no exhaust leaks on the post cat lambdas or close to them .. after that i'm back to the cats just ain't good enough .

Its possible .. although im doubting it that you have a running problem which is dumping too much fuel in the exhaust .. running rich basically and its damaged them or in effect " filled them up / coated the surface " making them less efficient .
 
Thanks Demort..

The CATS which came with the kit are these (they are 200):

https://www.design911.co.uk/pages/productList.aspx?search=3606109973

I took it back to the garage and they checked over it all, no leaks etc.. everything good?

is there a way of remapping the exhaust 'dirty' threshold (or something similar) as presumably these may not be as 'clean' as the porsche originals?

or how do I stop the light repeatedly coming back on (and potentially hiding a genuine problem in the future?)

Many Thanks
:)
 
We are now into the modding area and that's something i know nothing about .. i'm just a humble Porsche mechanic working on normal running problems .

I think there are sensors that have a mini cat inbuilt for the sensor .. or extensions that lift the post cat sensor up which in effect stops the problem ..

This is a question for the others here i'm afraid .. i can say whats going on but a fix on a non standard item is normally beyond me ..



:sad:
 
I've had a think about this ..

200 cell cats have better flow through of the exhaust gasses but are obviously not as good as the standard ones at cleaning the exhaust gasses .

I know the Mot guys at work have to get these stinking hot to get them to pass an emissions test .

BUT .. they don't have an eml light on as standard ...

I'm beginning to think the exhaust you have fitted is faulty .. maybe poorly sealed cats in the exhaust allowing the gasses to bypass ..

Either way it's not just the eml light problem you have but will they actually pass an mot test :?:

Separate post from my above one as its separate info .
 
200 cell are "high" flowing so, I would presume it needs a remap for the new parameters to be opened up. The car will naturally be burning more fuel in the mid range as the engine will run more freely. more air in more fuel dumped in. Result is , it's running rich and pinging the light on.

Has the pick up been more instant since you had it fitted ? And good torque between 3 and 5k?
 
As Demort says, some people use extenders (on the Lambda sensors) which apparently fixes the EML issue - although I understood this was more a problem with 100cell cats.
Mini-cats are available, that you screw in front of the sensors, to fool them. But I thought this was only needed when you do a cat bypass.

As Demort says, if your 200cell cats are triggering the EML, it suggests they arent doing much catalysing, so are behaving closer to a 100 cell cat. Have read on other forums (admittedly for other car-brands) that lots of people fail MOTs with 100cell Cats - so you may want to look into this. Is there a chance they supplied you with a 100cell cat, rather than the 200 cell version?
 
Two possible reasons

- cheap cats - you can pay £80 for a pair of 200 cell or £800 for a pair of 200 cell - this is the reason why some systems seem on the outset such good value.

- when you fit 200 cell cats instead of 600 cell for example, if your o2 sensors are old and not functioning 100% this can trigger error message now that you have only 200 cells. Tolerances can be triggered.

Ken
 
TTW, I've bought the same spec SS exhaust system from Design911 for my old Porsche 997.1 and worked without any issues, could just be bad luck
 
Ken .. its good to see you back .. you have been absent for a while from what i can tell and your input here is always appreciated .. i for one always try and read your posts .

For the OP then i think the general consensus is there is a fault with that exhaust and it needs replacing .

i know you can remap an engine but im unsure about remapping the post cat sensor as that's only there for save the planet stuff ..

Even so .. if it wont pass an emissions test then its no good .
 
deMort said:
Ken .. its good to see you back .. you have been absent for a while from what i can tell and your input here is always appreciated .. i for one always try and read your posts .

For the OP then i think the general consensus is there is a fault with that exhaust and it needs replacing .

i know you can remap an engine but im unsure about remapping the post cat sensor as that's only there for save the planet stuff ..

Even so .. if it wont pass an emissions test then its no good .
Click to expand...

Just so busy on multiple things especially latest Porsche tuning stuff taking all my time.

You can map out the post cat of course and any decent 200 cell cat will always pass MOT.

Still think if new exhaust that most likely failing post cat o2 sensors is a possibility even if they are cheap cats

Ken
 
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