Post Cat Lambda Spacer

[GTi_James]

mk4 aum with decat, i have the right angle spacer on after cat and no light, no codes. engine runs a lot smoother and i have noticed better MPG though dont know if thats a combination of hot weather as well. managing 150 miles a week with 2/8ths of a tank used only 

[ben.banks21]

get it mapped out. i now if you use a spacer on the agu pre cat sensor the car runs very lean.

You shouldn't need to space a pre cat 

i had to on my agu because the 3" straight through Exhaust system i brought from the US had the lambda sensor hole on the downpipe too close to the fire wall so i had to buy a 90 degree spacer which in turn caused it to run very lean.

It will have been running lean due to the false reading, was it a cheap decat? I'm running a 3" one from the US and had no such issues.

when my car went for custom mapping at rtech i had to have the lambda sensor hole moved on my downpipe because the 90 degree spacer was giving false readings causing the car to run lean.

[westylakey]

I have cable tied my post cat sensor to the subframe and left the blanking plug in the decat. No lights yet.