new to the forum here, looking for some assistance in fixing my friends 01 passat 1.8t. keeps throwing a check engine light. when i scan it the codes are for the maf or vaf sensor low system voltage. the MAF sensor and o2 sensors have been replaced. there was also a code for bank 1 system too rich. that has not returned. all the vacum lines look good from what i can see. but i have not got that far into it yet. any ideas would be very helpful.

Thanks

Matt