[billymade]

16806/P0422/001058 - Ross-Tech Wiki

You might try out some of the tests; in VCDS: (ageing testing, etc.)

VWVortex.com - VAG-COM procedures for testing the MAF, O2 sensors and catalytic converter

http://www.ross-tech.com/vag-com/m_blocks/030-049.html

Again, resolving the drivability and performance issues (fuel trims, etc); can affect others, as well. I guess, you can force the readiness settings and see what passes and fails:

Fuel Trim Info - Ross-Tech Wiki

Ross-Tech: VCDS Tour: Readiness

 

[JamieClay]

As an update - the misfires for sure have gone away and the 0422 code is consistent, triggering the CEL every return trip from work.

I've gone down the list on VWVortex and can't get the automated tests for 034 or 036 to run. It may be my AEG doesn't trigger by pressing and holding the brake pedal, or I'm missing some other trick to making that work.

So that's frustrating, add to that the current heat wave we're having and it makes doing this stuff even less 'enjoyable'.

But all the block testing up to 32-46 show nominal results.

The car is running ok, perhaps a little lack luster but it never really was a powerhouse to begin with.

I'm going to review my service manual later to see if there is some trick I'm missing regarding triggering the automated tests.

 

[billymade]

16806/P0422/001058 - Ross-Tech Wiki

So, when you try to run the forced readiness; does it "pass" or "fail" or not initiate at all? I have run into a "not ready" error; which typically, seems to happen when there is a trouble code present. There are certain parameters that have to be met; to initiate the readiness tests, one is there cannot be any error codes present, in the emissions system. So, the fact you have the P0422 trouble code; probably, would cause forcing them to not initiate?

Check out this snapon code readiness chart and guide: (look at page 23 for the aeg engine/new beetle):

https://www1.snapon.com/Files/Diagnostics/UserManuals/VolkswagenAudiReadinessCodeCharts.pdf

quoting from the above manual:

Check for stored diagnostic trouble codes (DTCs). Any codes set will
prevent readiness code completion. Repair all DTCs or other known
malfunctions before attempting to set readiness codes.

Check out this video; for a example of a walk through on a Passat:

https://www.youtube.com/watch?v=kqCYPSrV34Q

You could try external testing with a infrared temp gun and see if the temps are right (before/after the cat), confirming things that way. If you end up needing a new cat; we have had good luck with the brand Bosal, which has been a oem for VW in the past. You can look up your car in their catalog: (don't worry about the prices listed; you can find much cheaper prices online like on Amazon): Bosal Catalog

So far, everyone who has installed the Bosal cats; have had good luck with them and have passed their emissions tests with the P0422 trouble code being resolved for good!

 

[JamieClay]

Latest (and maybe last) update.

Took the car to the 'cat' shop to have them examine it, it was replaced only a couple years ago, and it was 'bad' in that it was rattling. Technically it's under warranty but I won't know if they'll give me any $ back until the manufacturer reviews the core. They may not if they think the failure was from the misfires. (I shouldn't have mentioned it, damn it)

The first day after replacing it I didn't have any more CEL issues (drove about 30 miles), but the guy at the shop told me I should replace the O2 sensors as a matter of course. He said he suggests every 80k, seeing as how Joose has 197k on her, I suspect they were overdue, plus they're trivial to replace (I mean when compared to replacing the transmission).

So I got Amazon to send me some, installed them and so far, 120 miles later no CELs, no faults and the car seems to be running smoothly, maybe better than ever.

In the end, I think the bad coil caused the misfires to damage the cat. The fuel pressure stuff, though a good exercise in sorting out the problems, wasn't the issue.

And through all this, the car still gets the same gas mileage. 22mpg - consistently. Go figure.

Thank you again for all your help!