So my legacy should be getting around 20 mpg city but is only getting about 15. It also has the slight smell of gas when you start it first thing in the morning but that goes away after you start driving. I looked around and the most likely suggestion was a bad o2 sensor. What do you all think of this diagnosis or any other ideas? I can answer any questions to help out.

Is your check engine light on? A bad 02 sensor, will definitely turn on the check engine light. It could also be a bad knock sensor.

 

How long since spark plug and plug wires been changed?

Replace your fuel filter.

The check engine light is on however thats registering for bad solenoids in the fuel tank. And i dont know how long since the plugs and wires were replaced, i got it used in october and the guy i got it from didnt change the plugs and he got it to fix and sell. Soooo its probably been a while. Can bad plugs really do all that?

 

And fuel filter??

check the clamps that connect the rubber fuel lines to the hardline at the manifold. I fix 3-4 a year for people complaing of gas smell when warming up.

 

Isaac

Thanks any idea on the bad milage?

The 99 2.2 uses an AFR O2 sensor in the front. If this is going bad, your mileage will suffer.

First tho, do the usual. Plugs are a must.

Then see how it does.

 

O.

Check rear wire harness on back right corner of car has not broken the harness for tank vent valve likes to break there and replace 02 if any doubt 02 controls feul delivery. Had a 99 impreza set codes for tank level senser and tank temp senser changed 02 and code went away was weird linked somehow

Or it could be because it is so damn cold out lately...I know my 98' 2.2 Impreza MPG has gone down the drain with this deep freeze 

I just checked mileage on my '93 legacy. City is usually 20 mpg, and now it is 15.6 mpg. It's been very cold here, 200 miles north of you (38 days with below-zero ºF temps so far this winter, lowest was -26ºF.) I attribute the loss in mileage to the number of cold starts and warm-up time. After you diagnose/fix the gas smell, check your mileage in spring.

Edited February 2, 201412 yr by BB's93LegacyL

Same here - 95 Legacy and mileage is down with the bitter cold

 

BB, I am just an hour west of you - about sick of this frigid stuff...

Well its been pretty damn cold Herr too, good to know I'm not alone with the milage, that'll save me money if its fine when it warms up.

My 98' 2.2 Impreza was running around 20 MPG with about a 50/50 mix of highway and "country" driving with the cold 

most of my driving is "country" - 2 lane roads, 55mph speed limits. Before the bitter cold hit I was running about 24-25 mpg, since the 1st "polar vortex" hit (and never really went away) my mileage has dropped to low 23s to high 22s

My MPG's dropped from 25 to 18, warming up the car, driving slower,higher friction from snow, ect.