Fault Code P0642

[Ads22]

Hope if anyone could advise, driving home yesterday get a dreaded warning light on dash with code P0642 Sensor Reference Voltage A low. Search online but seems like a vague code with no real certain culprit. Had my MOT however though and passed emissions thankfully. Ive noticed what feels like a slight lack of performance however that be just be me. The light is off now without having to clear but wondered if anyone has had this flash up. Currently getting 27mpg around town with no other codes flashing up. Boost seems to hit a max of 14psi and theres no nasty noises i can hear from up front.

[doylebros]

Have you read this guidance of possible areas?

http://wiki.ross-tech.com/wiki/index.php?title=17026/P0642/001602&action=edit&oldid=4196

[Ads22]

I have but it sounds like quite a few things that it may relate to. I wondered if there was any way i could narrow it down or if there is anything else I can lookout for which may help

[pudding]

Basically means 1 or more sensors hooked up to the 5V sensor reference line is goosed.   The MAP sensor and tumble flap motor both use that 5V reference line.  Given your symptoms, I would think it's the tumble flap motor.

[Ads22]

Basically means 1 or more sensors hooked up to the 5V sensor reference line is goosed.   The MAP sensor and tumble flap motor both use that 5V reference line.  Given your symptoms, I would think it's the tumble flap motor.

Thanks, is that the same as the intake manifold runner? Does seem to link as sometimes Im getting nice clean boost but then sometimes the delivery feels a bit lumpy.

[pudding]

Yeah that's the one.  I think it's pretty expensive so it may be worth checking the wiring etc first before cracking the wallet open.