[dAng! E90]

Hello everyone. I want to start by saying, I am a fairly good mechanic. I have worked in performace shops and been in the auto industry since I was 15yo. I have all the tools and a lot of know how when it comes to diagnosing a problem.

I just recently bought an '07 335i. It has 70k on the odometer, has CPO, never wrecked, had to HPFP replaced at 52k, bone stock. Four days after I bought the car the "SES" light popped on. It was giving P0174 System too Lean on Bank 1 & 2. I took it to my dealership and they said that the oil cap was not tight. They ran a smoke test and found no leaks in the vacuum system. I leave with the car and 2 days later, light comes back on. Now, heres something that was interesting to me...just normal around town driving, the "SES" light will never come on. I get on the interstate and set cruise at 70mph, I might make it 5 miles and the light comes on. This is how it happens every time. It doesn't seem to affect performace at all.

This is a really hard problem to explain but I was hopeing someone would have some input as to why I keep getting this code. All help is appreciated!!!

[E90SoFlo]

Take it back to your dealer and have them come along with a ride on the freeway with you. If its under warranty and you're still stock, then let them fix it for you.

GL OP

[ExpensiveTaste]

Most likely O2 sensors need to be replaced.

[dAng! E90]

Originally Posted by ExpensiveTaste

Most likely O2 sensors need to be replaced.

This is what I was thinking. But I wanted someone else to chime in.