lean bank 1 and bank 2?

[mazdamama]

i have heard that these codes could be caused by many problems related to egr, loose vacuum hoses, dpfe, and even dirty MAF sensors. These codes started popping up after i took off my exhaust system to replace my clutch. so i was wondering if this could also be caused by an exhaust leak? any advice would be greatly appreciated.

 

[skinner]

Are you SURE it started only when you took the exhaust down? Both banks indicated a seriously a/f mixture problem honestly. I'd double check everything....
I could give you a ton of guesses, but if they only started immediately after dropping the exhaust they'd all be wrong.

 

[Yellowsplash]

Yes, a leak at the collector can cause bad O2 readings. Tighten the collector bolts and ensure that there is no leak before proceeding on doing anything else.