29E0 & 29E1 Mixture Control codes when switching from 93 to E40 tune?


Jul 7, 2020
07' BMW 335i
29E0 & 29E1 Mixture Control codes when switching from 93 to E40 tune?

I’ve had this problem for the last several years, ever since I started running my custom E40 tune.

Every spring when I switch my car from my 93 “winter” tune, to my E40 tune, for the first few tanks of fuel, whenever I start the car up in the morning and let it idle for a while to warm up, it will pop up a CEL. When I scan it, it shows 29E0 Mixture Control Bank 1, and 29E1 Mixture Control bank 2. I clear the codes, and they never come back until the next really cold morning when I fire up the car and let it idle for a while. After I run a couple of tanks of fuel through it, it stops throwing the Mixture Control codes, and it’s fine all summer long.

The car runs great, logs look great, not a single issue as far as performance goes…..just trying to understand when I get these Mixture Control codes every spring when I first start running my custom E40 tune.

It only happens when it’s under 45f out in the mornings it seems, I’m guessing the DME has to richen the mixture up enough at idle with E40 in cool temps that the STFT’s are just getting out of range?

Would resetting the Lambda Sensors, Lambda Regulations, and Octane Rating adaptations after I load the E40 tune help to speed up the relearning process so I don’t get those codes for the first couple tanks of fuel?

I guess a log when it’s cold in the morning and idling would probably tell me some good info…it just seems like I’m always short on time and heading to work when the CEL pops up.

Anyone else get these mixture codes when going from a 93 tune to a E40/E50 tune in cooler temps?