I have a 2001 Discovery SE with approx. 100k miles on it.

My SES light is on with codes P0174 and P0171. I changed out the O2 sensors and cleaned the air flow sensor and still these codes remain. Also my cruise control works intermittently, most of the time not working. My mechanic cannot find a vacuum leak and all fuses are OK.

My plan is to change out the MAS and hope it clears both problems. Does anyone know if the MAS and CC are related via the ECU? Any other recommendations or should I just replace the MAS?

Thanks,
Dan

 

The cruise control not working is a vacum leak in one of the cruise vacum lines, easy DIY fix.

When was the last time that you had a GOOD tune up?
What grade of gas are you using?

 

I have owned it for about 2.5 years and 30k miles, no tuneups in that time.
Unfortunately I am burning 89/91 octane most of the time. Use 93 whenever I can find it which is not often.