99ML320 Check Engine Light

After getting an oil change the check engine light came on. The mechanic fixed it and then two days later it came on again. I also recently clean my K&N air filter, does this have to do with the check engine light coming on? I also did the ESS buttoning combination and the light is still on but the meter reads 10000. Can anyone give me some pointers, i dont want to bring it to Mercedes and have them charge my more $$$, I want to fix it my self?

Thanks
Mig888
99ML320

[tabo]

get any good mechanic to run the obd2 diagnostic on your ml and than if the codes p0171 and p0173 shows up replace the Mass air flow sensor its an expensive part.. but it'll solve all your problems