Guage and OBD Trouble Codes

[r_groove_99]

Hi everyone.
I have a 2001 X5 4.4. I bought it from a dealer about 2 years ago and have been having minor problems every so often. First is the gauge cluster lights for the oil service and the numerical ligths are out (not all but some). The dealer promissed they would go back on because the car sat without being started for a few months, but if not they would replace it. Of course once they got all their money they won't tough it and say its my problem now. To fix these lights do I need to replace the whole cluster or is it just replacing bulbs.

My other problem is the check engine light came on so I pulled the codes:

P0171 System too lean bank1

P0345 Camshaft Position Sensor “A” Circuit (Bank 2)

What do I need to do to fix these. The 171 it sounds like cleaning the MAF or replacing. Is this it or is there more I am forgetting?

When it comes to the 345 I don't know. Some people say change the exhaust cam sensor and some say change the intake cam sensor. Where do I start here????

Thanks in advance for the help.