So my SES light came on about a week ago, showing codes P0174, P0150, and P1174. I tried just clearing the codes twice but it came right back on after less than five miles both times. Also my mpg went down from 15-14 mpg to about 6.5mpg. Any ideas? I think that the drivers side exhaust manifold gasket might be starting to go bad but i do not think that it would make it throw those codes because it is not leaking very much at all. I checked one of the codes and it said that the motor was running too lean, which means it is probably dumping the fuel in and could be what is causing my poor mpg. Anyone got the answer?
cheers

 

Your O2 sensors might be going bad. Do you have the ability to read the O2 sensor outputs? When they are reading to high or low, is usually the sign they are going.

 

What do i need to read the sensor outputs? what is normal, high, low? I was also thinking that it might be a bad MAF, anyone know how to test if your MAF is bad?

 

If its reading 0% or close to it, you haven an issue. It shouldn't be over or under 2 digits... Basically, what are the readings on the MAF and O2 sensors? that will helps us determine whats wrong.

 

do i need a scan tool to check it? or can i use a volt meter on the wires?

 

I think you can use a volt meter to check the currents, I just find it easier to use an OBD scanner with the ability to read live data feeds.

 

At 110K, you are due for new sensors anyway. That is when they start to wear out. You can take the time to read the data if you want, but I would just replace. It is time, even if you have no faults.

 

At your mileage and with 1 02 already totally failed, start with 4 new 02's. Leave your MAF alone other then to check and replace your filter.

 

I realize that replacing all of the O2s at this time would be the best solution. That being said i do not really have 520 bucks. If i find out that the one is bad, and replace it, my codes should clear correct? Or will having one new sensor and three older ones not work? Also where should i get them? I assume that AB is going to be the best place... but i have a friend that works as a auto zone so i can get one from there at like half off. Would one of these work as a band aid until i get the money to replace all 4 with parts from AB? Thanks for your help guys cus i need to get this fixed, driving at a cost of 55 cents a mile is sure killing my wallet.

 

For what it's worth, you can get the whole set of 4 for something like $290 at AutoZone, last time I checked.