My 05 MCS will randomly turn on the EML and read a P1498 code. I can turn off the car and back on and it goes away. It may come on in 1 mile or 15. It is very random. I have replaced the plastic pipe connecting the SC to TB with a factory mini part. Nothing seems to fix this code. I Hope someone here can tell me:
1) why it is not a constant EML light. How can it
come and go if I have unmetered air after
the compressor
2) what triggers the P1498 code. If my
supercharger is pressurizing the intake
system how can it have unmetered air
3) can Map and Tmap sensors cause this code

 

Vacuum leak.

 

The P1498 can be caused by very small vacuum leaks or larger obvious ones. In my case I had a combination of small leaks that were hard to find using a smoke tester but was able to visually check when taking things apart. I would recommend rigging up an air pressure tester and spraying water (with a bit of soap mixed in) on the different areas of the engine and watching for bubbles. I found it easier to put the car in front end service mode to do this as I could see and touch lots of the common areas.

I found that my BPV to intercooler horn o-ring was flat and not sealing, oil cap o-ring failed the smoke test, intercooler boots were torn, intercooler was slightly bent (not allowing boots to seal evenly), and the fuel pressure regulator vacuum line all needed to be addressed. My car also had a brand new Mini supercharger duct/charge pipe and it was leaking air from the plastic weld seams. I ended up coating the seams with RTV and letting it dry overnight. Those seem to have fixed my P1498. I also recommend cleaning the throttle body and BPV if you have them out of the car (also check the vacuum line on the back of the BPV).

It is also my understanding that the MAP and TMAP sensors will have a different code thrown if they fail, but I suppose it could be possible that they could be bad. I would first spend time looking for vacuum leaks and then start testing the sensors since they don't seem to cause much of an issue very often.

Good luck and let us know how it turns out! The P1498 can be tricky to get sorted out sometimes!

 

+1 on the intercooler boots. They can have small cracks develop as they age, especially on the underside where it's not easily visible, and create vacuum issues.

 

Thanks for the great information. I will start my search for a vacuum leak!