2001 BMW X5 3.0i - Soft-Roading on the Cheap

[Jake]

I'm going to assume this X5 shares its same basic architecture (kcan) as the E90 - if thats the case then if you only throw parts at it then expect disappointment and an empty wallet.  These things are unfortunately so interconnected and the scan tools really dont tell you enough other than symptoms, leaving you in the dark for troubleshooting.  See if you can get your hands on a laptop loaded with the dealer software.

Case in point - a bad TPMS module took down the whole canbus and put the car in limp mode in my E91.  But the symptoms pointed to any one of a dozen causes so said the internet - water intrusion, a bad fuse box, other interior controller, etc, and the problem is they all are prone to failure.

But good luck.  I think this is a worthy challenge.

It's just a big E39, actually.

I've been on the receiving end of some super helpful people's brains at XOutpost. These cars are somewhat complex, but there is a big knowledgebase out there to help diagnose.

The "trifecta" lights are most likely tied to a bad ABS module, but we'll try swapping wheel speed sensors left to right first, to see if the easy button is the solution.

The SES and transmission lights are related. There is some funkiness in the air metering (be it from an intake leak, bad MAF, failing MAF, etc) that is leading to SES light. Because the ECU doesn't quite know what's going on, it gives the TCU a heads-up, and the TCU is like "well fuck it, let's go full line pressure just in case" while throwing up its own check light. I think the O2 is a good thing to replace, given it's telling me the specific one to change. Hoping that + intake boot will help the cause but am prepared to buy a new MAF too.