16805 - Warm Up Catalyst

[A4alaska]

did a VAG scan.

what is this and what is the fix? it is keeping my MIL on.

16805 - Warm Up Catalyst; Bank 1
P0421 - 001 - Efficiency Below Threshold - MIL ON



I'm getting the code on both banks.

[my_RS4]

Subscribed.. I've been getting this code on Bank 1. I clear it and it comes back next day. Clear it again, and it comes back a week later..
Clear again, comes back 3 weeks later. Sometimes it goes away by itself. I def ain't buying a new catalytic converter for this car. Is there any way to solve this cheaply?
O2 sensor spacers?? I dunno...


Sent from my iPhone using Audizine

[EuroxS4]

Replace catalytic converter(s).Unless you have 02 sensor faults that could throw the reading off.But you need to check which fault code sets first. 3.0 liter engine are known for having cats expire.Not so common on 1.8T's.

[imnuts]

Spacers on the rear O2 sensors can get rid of the codes as well, but doesn't fix the issue. Some ECU tunes also coffee this out, but you may or may not pass inspection depending on what your state checks and what tune you use.

Sent from my Pixel 2 XL

[Audiloko]

How can you know if the time is right or what kind of replacements do you make with the bad cats?