For those of you with AA headers...

[dailowill]

Am I the only one getting pre-cat 02 codes? I've had two mechanics look over the install. The original installer -- who is an AA dealer -- checked the O2 voltage and the other checked for exhaust leaks. The second mechanic found a small leak between the header and midpipe, replaced the gasket, and cleared the codes.

I've been speaking with AA for a while trying to diagnose the issue, but we haven't got too far. I've personally checked all the O2 wiring, reinstalled the tune, cleared the codes (with Carly for BMW tool) to make sure that it wasn't a fluke, but no luck. Both banks are throwing codes and its not immediate, but within 500-1000 miles. It also doesn't trigger the CEL immediately, but eventually.

The codes I'm getting are:
002C3A Lambda probe front catalyst 2, dynamic
002C39 Lambda probe front catalyst 2, dynamic

I've been told that its really rare for O2 sensors to go bad so quickly (40K) and both at the same time. AA says that the tune should only affect the post-cats. I'm thoroughly confused The mechanics say its the tune, the tuner says its the install/car. I'm not sure what to check next. Any advice is appreciated!

[631twentyeighteye]

Make sure your post cat sensors aren't mixed up. I got similar codes when mine were in the opposite bank than what they should have been. Highly doubtful that it's the tune as AA had tuned hundreds if not thousands of n52's.

I guarantee it's a hardware issue somewhere along the line.

[dailowill]

Originally Posted by 631twentyeighteye

Make sure your post cat sensors aren't mixed up. I got similar codes when mine were in the opposite bank than what they should have been. Highly doubtful that it's the tune as AA had tuned hundreds if not thousands of n52's.

I guarantee it's a hardware issue somewhere along the line.

The last time I checked, one header had matching black wired pre/post O2 sensors and the other had grey wired O2 sensors. That seemed right to me since BMW likes to carefully color code things. AA is also stating that the post cat O2 sensors should be off.

Anyone mind checking if their install is like that too? I already had two other mechanics say its correct...

[631twentyeighteye]

That sounds correct but they may have plugged them in incorrectly resulting in the codes. Despite the AA tune mine threw codes when they were mixed up as well.

That or they banged an o2 sensor and it died. I had a couple die shortly after install as well and I thought i was gentle with them.

I know how frustrating it can be, so don't think i'm trying to be an ass. Just trying to help you get it sorted!

[dailowill]

Originally Posted by 631twentyeighteye

That sounds correct but they may have plugged them in incorrectly resulting in the codes. Despite the AA tune mine threw codes when they were mixed up as well.

That or they banged an o2 sensor and it died. I had a couple die shortly after install as well and I thought i was gentle with them.

I know how frustrating it can be, so don't think i'm trying to be an ass. Just trying to help you get it sorted!

I appreciate your help! Did you change both your O2 sensors when that happened?

I really want to keep the headers since I like the power boost, but at this point, I'm not going to be able to pass any future inspections. It's just really frustrating when the mechanics blame the vendor and vice versa. I'm just stuck begging them to check things out...

[631twentyeighteye]

I did not. I found that my post cat sensors were mixed up. I corrected that and then a few weeks later one of those o2 sensors died. I then replaced one of those. A few weeks later a precat o2 sensor died, and i then replaced that. Then about a year later(a few weeks ago) that same precat sensor died and i replaced it yet again.

I'm still running original precat sensor and 1 original post cat sensor, both on bank 1.

Believe me i hear you. you can try a new bank 2 sensor 1(precat) sensor and replace that one alone. The codes you have show that to be the one with the issue. If it goes away than you're good, but if the codes linger than it lay in the post cat o2's.

You can also have your mechanic read the fuel trim's with a obd2 scan tool. This will tell him/you if any o2 sensor is actually dead, or if the o2's are mixed up. If one o2 is reading completely steady(they should fluctuate) than its a dead sensor. If one bank is read very negative and one bank is reading very positive, than the post cat o2's are indeed mixed up.

Hope that helps!

[Bimmer-Bob]

I did get some cat-related codes before the new tune was uploaded, but they were different and resolved by the tune. Good luck!

[Blacksport]

I had somewhat different problems...

After the header install, I had an idle that went up and down...I temporarily ignored it because 2 weeks later I installed the DISA intake...

I took it to Eurowerks, AA dealer in Deerfield, he flashed for DISA and headers...car ran fast but still had bumpy idle...

I replaced the upper OS's, figuring I damaged one during the header install...no difference with the new OS's...since the lower OS's were turned off, I removed them and put bung plugs in the headers...the idle was now smooth, but now I got a CEL, something about secondary OS heaters...John (Eurowerks) called AA and they said they have a flash to stop the computer from searching for secondary OS heaters...

I haven't taken it there yet, because the car is so fast and the idle is smooth...I installed a P3 Cars vent gauge, which monitors a bunch of stuff including CELs, and it can reset them...very cool...I pulled the speedo/tach bundle out and put a piece of A/C foil tape behind the CEL light, since I'm now monitoring CELs with the P3 vent gauge...

[3002 tii]

Originally Posted by Blacksport

I had somewhat different problems...

After the header install, I had an idle that went up and down...I temporarily ignored it because 2 weeks later I installed the DISA intake...

I took it to Eurowerks, AA dealer in Deerfield, he flashed for DISA and headers...car ran fast but still had bumpy idle...

I replaced the upper OS's, figuring I damaged one during the header install...no difference with the new OS's...since the lower OS's were turned off, I removed them and put bung plugs in the headers...the idle was now smooth, but now I got a CEL, something about secondary OS heaters...John (Eurowerks) called AA and they said they have a flash to stop the computer from searching for secondary OS heaters...

I haven't taken it there yet, because the car is so fast and the idle is smooth...I installed a P3 Cars vent gauge, which monitors a bunch of stuff including CELs, and it can reset them...very cool...I pulled the speedo/tach bundle out and put a piece of A/C foil tape behind the CEL light, since I'm now monitoring CELs with the P3 vent gauge...

Really interesting, at what rpm's were your idle bouncing? And do you think it was because of the AA tune settings or just by installing headers?

[Blacksport]

It would idle normally but every 5-7 seconds it would dip about 200 RPM for a second, and then back to normal idle...

I have no idea what caused it; it happened after the header install, before the DISA install and before the re-flash...

Like I said, removing the secondary (lower) OS's completely fixed the idle...

[Nafy]

Dailowill, were you able to get the issues fixed at the end? I am getting the same codes after supersprint headers installed. Thanks.

[dailowill]

Originally Posted by Nafy

Dailowill, were you able to get the issues fixed at the end? I am getting the same codes after supersprint headers installed. Thanks.

It's been a while but if I recall, the AA dealer didn't use the correct tune. After my mechanic replaced a gasket and I re-flashed the tune myself, the codes didn't return.

[Nafy]

Thanks!!

Originally Posted by dailowill

It's been a while but if I recall, the AA dealer didn't use the correct tune. After my mechanic replaced a gasket and I re-flashed the tune myself, the codes didn't return.

[gixracer]

When I installed mine and did the disa 3 stage it bounced for a bit. After my trip to The dragon it called down and settled in. If you are fluctuating after disa install check for small vacuum leaks