[Johnnybhoy7]

Looking for some knowledgeable help! Cars throwing fault code 4390 and after checking online the fault says - 4390 - Boost air temperature sensor - short circuit B+. Can't find anything anywhere online how to fix the problem. Is this the maf sensor??? Any help greatly appreciated

[Aragorn30d]

Its not the MAF, its a sensor in the silver charge pipe on the left side of the engine bay, that runs from the intercooler to the throttlebody.

Its either broken, or the wiring has become damaged.

[Johnnybhoy7]

Would it maybe just need cleaned? I've got a pre-lci 320d. Would this affect how the car runs or should it still run fine?

[Aragorn30d]

No its saying "short circuit" so the sensor is broken or there is a wiring issue.

It might put the car into a reduced power mode, i dont really know.

[Johnnybhoy7]

My cars running fine to my knowledge so far. I can't even find a replacement part online. When I type in boost temperature sensor nothing comes up

http://m.ebay.co.uk/itm/111772559333...&ul_noapp=true

Is it the small black thing on the silver pipe in that ad?

[Aragorn30d]

yep thats it.

Its item 10 on this drawing:

http://www.realoem.com/bmw/enUS/show...diagId=11_3658

[Johnnybhoy7]

Superb thanks! That gets me the part number to order it also. Thanks a million

[runnerswim6]

Originally Posted by Johnnybhoy7

Superb thanks! That gets me the part number to order it also. Thanks a million

Did replacing this sensor take care of the code? I just got this code after taking off the manifold and throttle body. Dunno if The wiring was tugged too much or just the sensor shot?

Thank a million