What do you make of these fault codes?

[rich_g85]

E46 BMW 325i.

P1620 - MAP Cooling Control Circuit Signal High
P0171 - System too Lean (Bank 1)
P0174 - System too Lean (Bank 2)

A cursory search for P1620 would suggest replacing the thermostat. But would that tie in with a too-lean condition? (mechanical noob here).

Thanks,
Rich

 

[rich_g85]

Thanks for the suggestions gents, but I think I'll just have it looked at.

On reflection I lack the experience to know what sounds 'wrong' and I can't afford to screw my engine up attempting a thermostat change as I need it to get to work!

 

[rich_g85]

Quick update on this and a couple more questions if I may. Car is booked in next week for investigation of the P1620 code (the MIL has incidentally now extinguished - sods law!)

Anyway, I thought I'd start it up out of curiosity and see if I could hear air being sucked in anywhere.

I don't know why, but I tapped the throttle and what I heard when I did I thought was unusual. It sounds like a belt slipping, before the revs rise.

And then a few seconds after I switch the engine off, there's another odd sound - like gasping air in.

I took videos of both so you can have a listen. I'd be interested in your opinions...

https://www.youtube.com/watch?v=JziVT7uvOHk

https://www.youtube.com/watch?v=P6dp0Ak7mtg