[edmfperez]

Hey y'all,

So a while ago the SES light came on after some routine driving. I pulled the codes using my Carly Pro OBD II scanner and I got this freeze frame report telling me that code "2C7E:AfterCat 02 sensor trim control, bank 1" had been triggered.

Rest assured, I searched the forums before posting, but have only come across a few dead threads with no actual solutions provided.

I have not experienced any misfires or anything like that of the sort, but I do experience fairly poor fuel efficiency with mixed driving (60% city/40% hw).

I have replaced the Oxygen sensor using a BOSCH unit, but the codes still remain; the SES remains illuminated even after a few hundred miles of driving since replacement on saturday.

I am completely stumped as to what to do and would appreciate any insight as to what I should do to remedy this issue.

Thanks!

[edmfperez]

Hey y'all,

Yesterday, I poked around the engine bay a bit because a friend told me about checking for possible vacuum leaks. Well sure enough, I found that the exhaust flap vacuum line from the brake pressure vacuum line was totally severed and off to the side.

I reassembled the line and sure enough upon startup the light was gone and the exhaust flapper seemed to function as factory intended. "Sweet," I thought to myself, "I bet the exhaust leak caused my 'Service Engine Soon' light to come on. "I bet that was the issue all along," or so I hoped .

The typical stutter at low rpm was now completely gone and the engine felt more powerful at low speeds; it felt like a completely different car. I truly believed that the vacuum leak from the line at the line on the driver side strut tower was the cause of my 335i's woes.

Well, about 7 minutes into the drive, the light came back on.

Shit.

"Okay," I remarked, "why I don't just clear it and go to work." I then proceeded to drive to work and idle a bit in the parking lot just to make the light wouldn't come back on. So far so good.

At around 5:30, I leave work and head to my home and realize why idling in the street that the light has come back on. Rats. This time, however, there is no low rpm stutter, no hesitation in power, nada.

So at this point, dearest forum goers, is where I currently stand. I wanted to avoid going to a shop to get things like this sorted out but as it stands it appears that I will have to do so.

[Franswua]

Hey! Did you ever get the issue fixed? If so, what was the cause of it? I’m having the same issue. I keep getting the 2C7E code and I can’t for the life of me figure out what’s wrong. The car behaves completely normal. It’s just that code.

[Nordic335M3]

anyone ever find a solution to this?