I've got two fault codes:

P0400 EGR Flow
P0420 Catalyst System Efficiency Below Threshold Bk 1

Other than single handedly destroying the environment, are there any other repercussions to these fault codes?

I consistently average 16 mpg. Would this crappy mpg be related to the above fault codes?

Other than the crappy gas mileage, she runs perfect. I don't want to replace the EGR valve and catalytic converter if it isn't going to improve my mpg.

Any insight would be greatly appreciated!

TIA,
Mike
1996 Legacy 2.5 GT

 

Id reset the ECU (remove the positive terminal from the battery for a half hour) to see if they come back. The EGR valve one might just be a fluke, but you could clean it. info here
http://www.scoobymods.com/forums/sho...ight=EGR+valve

Of course, with gas milage that bad then Therse probably something wrong with the front oxygen sensor. I suggest replacing that and you should get much better milage (I average around 25mpg)

Running some seafoam/cleaner through yoru car could be beneficial too
http://sl-i.net/FORUM/viewtopic.php?t=965

 

Did that a couple times and the CEL always came back on within 50-100 miles. Haynes says the valve should have only about an 1/8" of movement. My valve had more than twice that travel, so I decided to replace it. Just did that today, so we shall see how that effects my MPG.

O2 Sensor is good.

For schitz and giggles (I do have 221k miles on the clock...) I bought some Seafoam and put some in today via the PCV and dumped the rest in the tank. Holy crap! It made a noticeable difference! It accelerates much smoother and doesn't seem as 'bogged down'. Best $5.44 I've spent in a long time. Thanks for the heads up sha_zapple.

I should know with in the next few days if any of this has improved my MPG.

Mike

 

Awesome, glad I could help!
Im a poor university student, so Ive been keeping my foot pretty light and I've managed to get 360km (221miles) out of 30 liters (8 gallons). Also Ive kept the heater off, which seems to make a difference.