lean

Hi everyone. I'm New to this forum. Today I built a DIY smoke machine to find the air leak on my 2008 VW Jetta 2.0. I was successful in finding a leak but dont know what part this is or how to go about fixing it. I'm guessing it's an "o" ring or something like that under the circular cap in...

I have a 2.0L BBW Engine and periodically the check Engine light comes on. When I check the OBDII message (P2177) it is defined as "System too lean off idle bank 1". Has anyone experienced this error message? I suspect that it has something to do with low fuel pressure. I suppose the best thing...