The Cars thrown this up twice now so I know its not going to go away.

16804 Catalyst System Bank 1: Efficiency Below Threshold: P0420

16795 Secondary Air Injection System: Incorrect Flow Detected : P0411

Well I know what the secondary air system is about, I have bought the forge backing plate and some fuses to remove the whole gubbins.

But my question is really just to check that the cat error code is link to it? and no somthing else.

Thanks for your help.

Check this. http://wiki.ross-tech.com/wiki/index.php/16804/P0420/001056

I do have a full blueflame system 200 cell about a year and a half old so the cat should be fine.

Could be one of the C02 sensors. Did you read the vwvortex link on the above Rosstech link?

Catalyst efficiency below threshold bank one usually indicates to the pre cat lambda sensor is duff mate.

Ok thanks for that guess I need to investigate more not sure what.

But the fault are not linked then?

As long as I know that I can deal with the secondary pump 1st.

Well as far as I know the SAI is there to help warm up the cat on cold start up so there is a link between the two. The usual problem with the SAI is the rivets on the housing failing which is an easy fix, but a lot of people to remove the whole system instead.

Hi,

 

i have something same...

 

 

First when that engine yellow light went on i deleted it because there didnt seem to be nothing wrong with the car but it has came back now.

 

Can you read out, what is the problem here?

 

 

I have chanced catalytic converter few months ago.

 

 

2001, 1.4, 55kw  Skoda Octavia

 

 

 

here are pictures about them.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited 13 September, 201312 yr by DeltaPapa

Could also have a air leak or faulty maf sensor,

Just because fault code says its that doesnt mean it is