I must not be living right or life has a funny way of trying to tweak my patience. Diesel exhaust smelled up the cabin again today and low power/fuel economy since getting the X back less than a week ago.

I went on a search for the smell myself. Low and behold, I found it!! It was not very difficult either. Any technician could have found this if they would have spent a few minutes. Under the faux intake runner/plastic cover I found lots of diesel soot. If you have not guessed where the soot is coming from yet......it was the EGR cooler. AGAIN! Instead of being cracked in the usual place the others failed, it was cracked closer to the area where it couples together. Unbelievable. The updated design seems to have fixed one problem, but perhaps weakened another area.

Now to the lower power/poor economy: Hooked my AE scanner up and pulled any and all codes and used the enhanced features to look at all the engine sensors. I found some weird stuff like telematic troubles, radio fault codes and display fault codes. Although those systems seem to be fine. After looking through the sensors I found the air intake temperature was showing 419 degrees. This is not correct. I drove the X with the scanner running and logged the data for a few miles and returned home to review it. The intake air temp stayed at 419 no matter what was going on. There are two intake air temp sensors. One before the turbo and one after the turbo/intercooler system. The one I am having trouble with is the one before the turbo and it is built into the MAF (mass air flow) sensor. The fuel economy/low power has to be the result of the engine seeing such a high temp, less dense air charge and adjusting the fuel trim. The insidious thing for us X5 owners is...you will not get a trouble code if the temperature side of the sensor is faulty. Just lower power and fuel economy. Mine dropped from a solid 24.5 to no better than 21.5. The X feels throttled, not torquey and as strong as it was before.

Oh, I almost forgot...there is a secondary air system that is showing in the yellow zone. This may be an anomaly of the scanner and I will contact the manufacturer of it tomorrow and inquire. The normal range for the system is between 15.5 and 22. It is at 20.6. Nearly faulted. I did not know there was a secondary air system on this engine, but I do know this has never been in the system scans before.

I will make a separate post for those who search for lower power and intake temp sensor issues.