3.0 Manual X5 First Post/Question

[JCL]

Always work to diagnose the problem before throwing parts at it.

While the Lambda sensors are 02 sensors, the code referring to them doesn't mean they are necessarily bad. It means they are reading out of range. That could be because they are bad, or because something else is causing a problem that causes them to read out of the expected range. A clue is that both are bad. You wouldn't expect both to fail at the same time, so it is worth looking for the root cause.

Once you have the codes, you follow a test plan to determine what the cause of the codes and problem is. Without a test plan, reading the codes tells you very little.

[Bayerische E53]

JCL is right. I was getting lambda codes and all it ended up bein was a broken DISA valve (vacuum leak).

I still maintain that it's most likely that OP has a vacuum leak.

OP, best thing to so is fish around for leaks. You should be able to do this fairly easily by checking for loose/cracked hoses and elbows etc. I'd take out the DISA valve and check to make sure it isn't broken. The CCV (crank case ventilation system) could also be it. If you're stumped, take it to your indy.

[DSNoad]

Well a few updates on this issue since it started a few months ago.

1. Needed to have the problem solved immediately due to work and took it to the only place that had an opening (the dealer) they ran tests and decided it was the clutch, which seemed odd. They opened it up, took a look at the clutch and called me to tell me they were 99% sure it was the problem. Being dumb and running out of time I decided to throw money at the problem in hopes it would fix it. Big surprise - it didn't.

2. After picking up the car the check engine light came on immediately. Threw codes or both downstream O2 sensors. They said since it happened while it was there that they would do the labor or free if I paid for parts. Bought them from an alternate vendor and they swapped them.

3. The problem is still here, although a bit less noticeable. When I approached the dealer about this they told me the car seems fine, but I KNOW deep down that the car performed better before all this. No RPM drift and not sluggish at all. I replaced the plugs for good measure but the car feels the same.

Any more advice on checking for the vacuum leak or on how to pin this on the dealer? They didn't fix the problem and don't even recognize there is one now. Would someone mind clarifying on what spots to check for a leak?

[Ricky Bobby]

How many miles on your X?

I would check your DISA valve to see if the o-ring is allowing a leak, as well as the lower intake tube elbow for leaks!!!

Those are the 2 most popular spots on M54's