[khanmohammed]

So I was getting ready to go the emissions again. Car has a high flow catted downpipe. I was able to pass everything except the catalytic heater efficiency and O2 heater. I didn't start the drive cycle from a cold start so that's why the evap is not ready still (it was ready when I went to emissions the first time)

Car had BM3 Stage 2+ tune so I went and changed the CEL Monitor config to "OEM" instead of off. Drove it in comfort mode not passing 3k RPM for 10 miles, and did highway cruising speeds.

Still says "Catalytic Converter: Efficiency below limit value"

Does flashing back to Stock Stage 0 help fix this?? If this doesn't work then I have a 90 degree o2 extension that I was going to install.


- 2018 340i xDrive M Performance Edition

[Jvac]

It isn't going to pass with that pipe on there, unless your city or county allows for a pass with one or more readiness monitors failed. There are quite a few threads on here about the topic, but none have a long term fix beyond reverting to stock or a higher end downpipe that will meet emissions standard

[khanmohammed]

Originally Posted by Jvac

It isn't going to pass with that pipe on there, unless your city or county allows for a pass with one or more readiness monitors failed. There are quite a few threads on here about the topic, but none have a long term fix beyond reverting to stock or a higher end downpipe that will meet emissions standard

I'm allowed to pass with one not ready.

[Jvac]

The 'catalyst below efficiency' code is going to keep coming back before you have enough of your monitors ready to pass inspection. Years ago you could just clear the codes and quickly drive into the shop before they came back, but now the readiness monitors make sure you drive around long enough to flag any deficient systems. Bm3 by itself doesn't offer a path around this