NZ BMW 368 Report post Posted March 3, 2017 Hi Team, I've had quite an annoying lean running issue for a little while. I state up front that I cannot remember the exact code the car is throwing but suffice to say I've been advised that it's 'out by about 2%' on the lean side which is triggering the CEL, according to the live data. There are no apparent physical symptoms in how the car drives. So far I have had my mechanic do the standard smoke test which has not shown anything obvious and we've replaced both the oil separator valves/diaphragms which are a common point of failure. The most confusing issue is that the CEL is not consistent. It comes and goes. What is even more confusing is that just before Christmas when I had the oil separator work done and everything reset I then immediately took the car for a 4000km road trip to the bottom of the South Island and back, with zero CEL across lots of long, hot runs. Then, as soon as I'm back in the city a few hundred kms later, it's back. I know it's pretty futile trying to diagnose this kind of stuff from a keyboard but can anyone point me in the direction of where to go from here given that it seems to be more prevalent in city driving based on past experience? I'm leaning towards a slightly lazy O2 sensor, which I can probably bring in and have changed relatively cheaply. Thanks in advance! Quote Share this post Link to post Share on other sites
Olaf 3235 Report post Posted March 4, 2017 air leak? I'm guessing. I'd have it diagnosed by a specialist. Quote Share this post Link to post Share on other sites
NZ BMW 368 Report post Posted March 4, 2017 1 hour ago, Olaf said: air leak? I'm guessing. I'd have it diagnosed by a specialist. Maybe, although you would think having the professionals do a smoke test previously would find this. Im really more interested to hear if anyone has had a lean issue that only throws a code in city driving, it's really weird. Quote Share this post Link to post Share on other sites
Olaf 3235 Report post Posted March 5, 2017 23 hours ago, NZ BMW said: Maybe, although you would think having the professionals do a smoke test previously would find this. Im really more interested to hear if anyone has had a lean issue that only throws a code in city driving, it's really weird. sorry, selective reading. missed the bit about the smoke test... (dunno how) Quote Share this post Link to post Share on other sites
