Decat

[jockgti]

Hi,if i fit a new downpipe and decat obviously that will flag engine management lights on dash,did i read somewhere that this can be sorted with a quick remap fix? if so what happens when its MOT time and the cat goes back on?

[Dave_IOW]

First part is a yes.

2nd no idea

[barrym381]

most de-cats systems are a simple bolt on-off so easy swap come mot time but as long as emissions are ok shouldnt be a prob

[jockgti]

i was wondering more if the bit of code they change/delete would make everything work ok when cat is put back on

[daz veedub]

when i had cat put back on for m.o.t had no lights come on 

and same when decat put back on after had no problems

[magsmagsmags]

as far as i know all thats done when they map the light out is increasing the threshold on the second lambda so when its reading high emissions (which would normally be as a result of a knackered cat) it doesn't show anything. If that is the case, then putting the cat back in still wouldn't show any lights as it'll be well within the tresholds

[jockgti]

ok cool a downpipe and decat it is then

[km]

am i right in saying early golfs only have 1 lambda sensor so there would't be any lights anyway?

[stevelfc]

yes only 1 lamba sensor but this still can bring on the engine light or put it in limp mode as the sensor wont be reading the exhaust gases

[Wazzzer]

no it won't as they don't have an engine management light 

Also they read the gasses before the cat so a decat doesn't affect the ECU at all