VCDS error and lambda question

[S3Powerxz]

Hello guys!
I have S3 8l AMK engine and today i scanned the car with VCDS (haven't done it since i changed my post cat lambda which was not working)
So i got error:
16804 - Catalyst System; Bank 1: Efficiency Below Threshold
I guess my cat is gone. Now im thinking of decat with straight pipe, but im worried about the post cat lambda.
Is it possible to remove the cat and keep the lambda happy (no engine check on)?
I heard something about lambda spacers, but i couldn't find any useful info about them.

 

[<tuffty/>]

Typically code out the CAT codes for the post CAT lambda on a remap..

Spacers are a bit hit and miss but they do apparently work most of the time

<tuffty/>

 

[desertstorm]

I fitted one of these when I changed to a decat 3 inch system on my TT and it kept the EML off for several weeks till I got the car remapped.
http://www.ebay.co.uk/itm/M18-x1-5-...tension-Extender-Spacer-Exhaust/122573829168?

 

[Fordy51]

It could be as simple as
a leaking flexi pipe,
blow between the downpipe and cat flanges,
Or rear lambda probe wiring to the ecu gone black inside.

 

[Stuart B]

if you are considering a decat / sports cat and you still have the original twin cats and twisty downpipe - you will want to also change the downpipe to a 3 inch downpipe. you might really struggle to get the old cats off or even getting the old post cat sensor out.

being LHD I think you have more space for a greater variety of downpipes.

 

[vanilla_ice]

Typically code out the CAT codes for the post CAT lambda on a remap..

Spacers are a bit hit and miss but they do apparently work most of the time

<tuffty/>

A spacer hasn't worked with mine running a 10 year old “Stage1” Jabba remap.

Is coding out the post CAT sensor DIY-able?

I know it's not ideal, but can any harm be caused by using the car with a CEL related to the post CAT sensor?

Thanks.

 

[badger5]

Hello guys!
I have S3 8l AMK engine and today i scanned the car with VCDS (haven't done it since i changed my post cat lambda which was not working)
So i got error:
16804 - Catalyst System; Bank 1: Efficiency Below Threshold
I guess my cat is gone. Now im thinking of decat with straight pipe, but im worried about the post cat lambda.
Is it possible to remove the cat and keep the lambda happy (no engine check on)?
I heard something about lambda spacers, but i couldn't find any useful info about them.

OR airleak upstream of second lambda sensor..