Why am I getting 29F4 & 29F5 with catless downpipes?

[QueenCityLurker]

Hello -- I'm MHG stage 2+ mapped. Can anyone tell me why the tune is reporting 29F4 and 29F5 which is essentially the generic catalyst efficiency below threshold? I thought the cat check was disabled in MHD? I have the tune set to Aftermarket Downpipes.

A MHD scan shows 29F4 and 29F5 as shadow codes.
I also have 29E1 Mixture control 2 as an active code but no SES light.

I'm guessing that my bank 2 O2 sensor may be in early stages of failure, but I am perplexed on why the tune is even returning a catalyst efficiency below threshold code when I didn't think it was even checking that.

Thoughts??

[mattlal]

Hey, did you find what the problem was? I got these codes yesterday after my first hard pull since catless downpipes. It was a 0-60 launch and right when I shifted in second at 6500rpms there was a noise under the car like a small bang. And right after that I lost all boost. This morning I reset adaptations and cleared the codes and still no boost, but the codes didn’t come back. Anything would help at this point.

[Brandon_2011_135i]

I had a similar issue, I’m on MHD stg 2+ and assumed the downstream sensor would simply be disabled, but I kept getting codes, even with the O2 spacer. Eventually replaced downstream O2 sensor and that resolved it. I’m wondering if the constant heat cycling makes the wires fragile and installing my HFC damaged them. Old O2 sensor I assume was original, 34K miles on the car when I got it.

[Brandon_2011_135i]

Originally Posted by mattlal

Hey, did you find what the problem was? I got these codes yesterday after my first hard pull since catless downpipes. It was a 0-60 launch and right when I shifted in second at 6500rpms there was a noise under the car like a small bang. And right after that I lost all boost. This morning I reset adaptations and cleared the codes and still no boost, but the codes didn’t come back. Anything would help at this point.

Need more information. Stock charge pipes or intercooler? Recently changed to stage 2?

From what I’m gathering putting high boost on stock components won’t take long. Maybe you cracked plastic somewhere you can’t see?