Fault code HELP!

Evening all,
Had a diagnostic check on my '99 110 TD5 because of poor starting and idling until fully warm.
Fault codes are as follows:
0121 Air flow meter circuit value to low
018b Road speed signal currently active missing
Any help to find out what this means would be greatly appreciated as this is my work vehicle and needed back on the road asap
ATB
Phil

0121 Air flow meter circuit value to low = the air flow meter isn't working. It is found in the air intake.

018b Road speed signal currently active missing = Probably means the road speed sensor has also failed - not sure where these are but they will be somewhere on the transfer box side of things.
Hope this helps more than the other replies so far

Thanks for that,will look into it.