Advice on Ox sensor codes and whether Catalytic converter(s) could need replacing

[TurnAround]

2003, 3.0i M54, 117,000 miles, PowerChip ECU remap is only mod



2 weeks ago the SES light came on. Checked codes with my Peak Research R5. Rest them. Same exact set came back within 5 miles. Reset again. Same codes again soon after. Summary of what I got:

• • Misfire on all cylinders
  • 02 Sensor Adaptation Limit, Cyl 1-3
  • 02 Sensor Adaptation Limit, Cyl 4-6
  • 02 Sensor Control Limit, Cyl 1-3
  • Catalytic Converter Efficiency, Cly 1-3

From this list, I couldn't tell a difference between upstream 02 sensors, and downstream. Just the bank difference.

After researching this board I decided that I would just replace all four 02 sensors, since the car has 117k and the sensors are designed for ~100k. I could have done upstream and waited, but I drive the car on long trips and don't want to risk stranding or long drives with SES light on. I paid my indi to do it. I own two other M54s and the next one that needs them, I'll probly do the upstream 02 sensors myself. Anyway, they replaced them Dec 31st, and I ask them not to read the codes and just do the replacement... because they charge $90 to diagnose, and I like to skip that step when I can if my Peak tool is uber clear on the codes.

When I got the car back it was still running rough, which surprised me. SES came on shortly there after, and the same codes came up again. Oye.. Reset, and then they came up again. Crap.

So the sensors and labor are under warranty, but, now I've been researching catalytic converter issues on this board. I'm going to be shitlessly bummed if my cats are bad, due to the unbelievable cost of those things, plus labor. The car goes back in on Monday Jan 5, and this time I feel I don't have a choice but to let them fully diagnose it, but.. I want to arm myself with the max information before going in, because I'm reading here that several of you have had similar issues, and the subsequent diagnosis was long and drawn out.

I'm having them replace the fuel filter (just for similar preventative reasons.. save the fuel pump). Mentioning, just in case its related.

Spark plugs were replaced the other day, along with the 02 sensors.

I'm reading it could be the cam shaft sensor(s). Got it, understood. I've replaced those on my other two Z's (Though I'm not getting those codes on the X).

I hear that it could be the vaccum system, or a manifold leak, or maybe even a gas cap. Got it.

Any other advice? Thanks!