warning lights advice....
 

I need some advice on multiple warning lights on my V40 (automatic)...

the lambda light comes on randomly so I took the car to a volvo speciallist who plugged it into the diagnostic computer and told me it is the oxygen sensor which has a problem, not sure why the light only comes on some times though ?

he did tweak something and said it may have just been loose, the light still was on though so was contemplating booking it it for the sensor to be replaced when......the transmission warning light has started flashing.

I had put the car in a low gear to get up a hill, the car didnt like it and I had to reverse back and go up normally but ever since the up arrow is flashing !

I reluctant to go back and pay another 50 pounds to be given bad news, any ideas on making all the warning lights go away without taking the bulbs out and without having my pants pulled down by a volvo dealership !?

any advice much appreciated