Down on Boost ?

del mar

Junior Member

I noticed that the boost gauge only just goes into the yellow, whereas it used to go well into the yellow and on occasion would just touch the red. I know the gauge may not be the best measurement of actual boost, but it doesn't do something that it used to do.

Johnny's blog suggested that the SEM boost solenoid was prone to failure and he did replace his, with a Turbosmart one. The OEM one looks like a fairly cheap bit of plastic.

Has anybody replaced theirs ?
German suppliers quote a very reasonable €1500 for a part that is listed at £70, although are there any left ?




Junior Member
In my experience when the SEM fails you get no boost at all.

I think finding a new SEM is next to impossible these days, maybe try some Saab dealers as the where used on the 9000.

Having some boost but not full boost could indicate many other problem areas.

  • Wastegate not closing properly
  • Leak in intercooler or boost pipes
  • Leaking blow off valve


Junior Member
Check the connector to the knock sensor , they known to be loose or corroded , this then ,limits the boost. I know this because Maserati shed told me about it and it solved my issue.