M54 Catalyst problem

[birch1]

Just got my project '03 530i working well enough to drive. After completing the drive cycle to enable all readiness lights, the cel comes on. This time its p0420 and p0430. Scanning it with inpa shows errors 245,246, 233,234. It looks like there may be a problem with the secondary air system too.

From what I know these are independent problems? Efficiency is evaluated at 2k rpm at highway speeds and the air system is evaluated at idle and is only used at start up.

The car has 212k miles on it. I replaced the o2 sensors with used ones that have about 110k on them. I also replaced the maf with a used one that had been recently purchased. The engine runs slightly rough at start up and then has a very faint vibration at idle when warm (no idea what's normal on these cars). Short term fuel trims are 5.5 and 6.3 for banks one and two. Long term is -0.8 and 0.

I can post o2 data if anyone wants to see. I'm hoping the cats are fine and it's a problem with something else.

[birch1]

Not sure what inpa code items are so here's the output on two of them.

233 catalyst efficience Main cat. Bank 1
N_32 2432 rpm
MAF 185.20 mg/stk
TCO 91.50 Grad C
TIA 32.69 Grad C
aufetreten vor (rel. BZ) 4.10 h
catalyst efficience to small
---
---
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Error to relevant
Error debounce
Error currently available
Stat. Error
Errorcode: E9 71 01 28 4C 22 BA 6C C7 A3

The other code is for bank 2

Upon inspecting the secondary air valve I realized I had disconnected the hose previously to inspect it and had run it for a minute disconnected causing that error. Basically the secondary air errors are irrelevant to my problem and should be ignored.

[Ed CT]

I've gotten those codes 3 times, and new pre-cat O2 sensors resolved the problem. First time was at about 100k miles, got codes for both banks. Second at around 180k miles was for only one of the banks. If you're due for oxygen sensors anyway, might want to give it a try.

[birch1]

New upstream o2's didnt make a difference. Pulled them out today. Bank 1 is destroyed. Theres a big piece missing and its melted. Bank 2 looks clogged. Must be from the previous owner running it way rich.
Has anyone had luck welding in aftermarket cats?
WIN_20190517_11_12_15_Pro.jpgWIN_20190517_11_16_40_Pro.jpg

[Ed CT]

Well, that sux. From what I remember reading, not all aftermarkets will work with this E39 system. Maybe someone will chime in with their aftermarket experience. You might find some info on viable aftermarkets in a board search here, too.

[edjack]

I have CA-approved Magnaflows on my car. So far, so good.

[birch1]

Did you use the complete header or the weld in?