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View Full Version : Check engine light and decrease in gas mileage



phung717
01-24-2009, 07:58 PM
I have a legacy 95 lsi and my check engine light has been on. Since then I have also noticed a drastic change in gas efficiency. I use to get about 25mpg and now I'm getting 18mpg. I was thinking it may be a bad o2 sensor but entirely sure. I took it to autozone hoping they could diagnose the problem but apparently 95 is different obd so no go. I have scheduled a check at the subaru dealership so I can have it done. They are charging 80 just to diagnose it.

So I'm just wondering if anyone has encountered the same problem as I have. Thanks!

nipper
01-24-2009, 08:10 PM
95 can be OBD1 or OBD2. If you have a little plug at the left side of the bottom of the dash its OBD2.


Most likely its the O2 sensor.


nipper

Okin DaVanh
01-25-2009, 07:22 AM
95 can be OBD1 or OBD2. If you have a little plug at the left side of the bottom of the dash its OBD2. If you have 2 O2 sensors is another way of knowing.



Most likely its the O2 sensor.

I wouldn't bank on it tho.We had the same symptoms on our BK awhile ago. After I scanned it, it turned out to be a bad Knock Sensor. Get it diagnosed, and if you're mechanically inclined- repair it. If you're not, post here and we'll try to help.

phung717
01-25-2009, 12:05 PM
so autozone is able to check obdII? The guy didn't look at my car, heard it was a 1995 and said it is a obdI and can't check it. I guess i may have to pay him another visit. There is a plug located under my dash, so i'm guessing my LSi is an OBDII.

phung717
01-25-2009, 01:33 PM
brought it back to autozone and they checked it. Ended up being a code for the Cat.

nipper
01-25-2009, 03:58 PM
ok OBD2. Cat code is usually the front O2 sensor, which either one would be possible at your mileage. Also if you needed a cat at that mileage and age you would be replacing the O2 sensor anyway, so start with the cheapest thing first, the O2 sensor. Replace the front one with one from OE (www.1stsubaru.com (http://www.1stsubaru.com) last i looked had them on sale).

nipper

phung717
01-25-2009, 08:39 PM
so you think it'll be a smart idea to just replace both O2 sensors? My uncle said he could pick up both O2 sensors from the junkyard for maybe $30. Or should i get a new set?

phung717
01-25-2009, 08:44 PM
BTW, i would like to thank you guys both for the help, i appreciate it. This saved me over $100. I'll keep you guys updated with the O2 sensors, i won't know for another 2 weeks if that is the problem b/c i am back at school and can't get it worked on until 7th of Feb. when i'm back home.

Plays_with_Toys
01-25-2009, 08:46 PM
You can purchase a bosch one for $50-60. I know advance auto carries bosch, not sure about the other stores. There'll be two available, one with a plug (about $10 more) and one with out. If you buy the one without a plug, you'll have to splice wires into your old plug. Being lazy and not wanting my sauder job to affect voltage readings I bought the one with the plug.

nipper
01-25-2009, 08:54 PM
BTW, i would like to thank you guys both for the help, i appreciate it. This saved me over $100. I'll keep you guys updated with the O2 sensors, i won't know for another 2 weeks if that is the problem b/c i am back at school and can't get it worked on until 7th of Feb. when i'm back home.


Wait till you price a cat, we saved you more more then that (hopefully). The front one should be OE, the rear can be anything. I dont like junkyard O2 sensors as odds are thats one of the reasons the car got there, or the car burned oil, or blew a HG and contaminated the O2 sensors.


nipper

jey
01-26-2009, 12:46 PM
Yes just get a new sensor for the front - if you end up with a bad/lazy O2 sensor from the junkyard you may never see that 25mpg again.

Navi271
01-26-2009, 03:33 PM
So I definitely have the same problem. I have low mileage (18-20) in a 95 legacy. Check engine light is on. The dealer diagnosed it as a cat failure. If you clear the code the check engine light goes off but then comes back on in about 200 miles..
I'll replace the O2 sensors also and share my results, which will probably be in a few weeks.
I HATE this low mileage!! :smt013

Huffer
01-26-2009, 03:44 PM
The dealer diagnosed it... what code did they pull?

FWIW, the cost of an OEM cat - $699. Cost of OEM sensors - $100 each.
No wonder a dealer will replace the cat along with the sensors. 3hours minimum, $80 an hour, $1200 total + tax.

hello...

LegacyRob
01-26-2009, 05:26 PM
I've been keeping track of my mileage and I'm getting an average of 16mpg (02 lgt), so i just replaced the front 02 sensor. will see if it goes up any. I was wonder if I should reset the ecu? any thoughts?

GTDrifter
01-26-2009, 11:01 PM
ive been having the same problem too...dealership told me it was the knock sensor, got it checked during my inspection at another dealership and it wasnt...almost got charged $50 for the check

been to 3 garages...nobody would tell me what it is......thanks for posting ill replace my sensors too

Navi271
01-28-2009, 12:45 AM
honestly i have no idea what code they pulled.. they might have it on the receipt i got but its not with me at college at the moment.. I'll take a look see.
The dealer said it would be better getting aftermarket cats, THEY said they could get some for about half price.. so like $600 + tax.. still sucks
I thought i remembered them saying it would be somewhere around $500-800 (rough estimate) to replace BOTH cats???
I'll have to get that receipt this weekend!

Navi271
02-05-2009, 04:10 PM
ok so i never found that receipt..
but ill be replacing the sensors with new oem ones, then if that doesn't work ill be getting aftermarket cats.. someday..

steamboat26
02-05-2009, 06:51 PM
EDIT: Sorry to hijack the thread, probably wouldve been better to make my own in a more relevant section...

Just out of curiosity as far as your guys low gas mileage goes- is that with combined city and highway driving or just city driving?
I almost exclusively due stop and go city driving (rarely on the highway, so rarely over 40 mph) and I have pretty much always gotten 17-19 mpg city.
My few extended highway drives are right in line if not better than estimates for the 95 LS, but my city mileage has always been way below estimates- no CEL (other than intermittently working VSS).
Any ideas? I always kinda figured that 18 mpg was to be expected from a heavy-ish AWD sedan in stop and go 25 mph traffic....but maybe something else is going on...?

phung717
02-05-2009, 09:15 PM
yeah, 18mpg was mixed driving with CEL on...

what you're getting, seems a little low for my liking. For pure city driving, i usually expect my car to do 20mpg... and 26mpg pure highway. BTW, i only use 92-93 octane... if that even makes a big difference?