Time for a new O2 sensor?

I've been thinking about this a lot lately...My O2 sensor has never been replaced. There's a little over 95,000 miles on it. I know i should get a CEL when it's bad, but...
1. My gas mileage isn't as good as it was when i got the car.
2. Seems like i've lost some power.
3. A long time ago when i bought an A/F ratio gauge from Summit, i hooked it all up and the damn thing kept reading LEAN. No matter if i let it idle, cruised or got on it. I think maybe once or twice it jumped to Rich for a split second. I took the damn gauge back because i found it annoying.

I'm asking this because these O2 sensors aren't cheap. I think the cheapest one i found was maybe $85 and it was some off brand. I'd like to get a Denso if i'm going to replace it.

Any suggestions?

You wont necessarily get a CEL when its bad. The ECU wont throw a O2 sensor specific DTC unless the heater circuit fails. You'll get a fuel trim malfunction DTC if it really stops cycling. But it can still be in piss poor shape and the ECU wont know about it. Based on your symptoms, mainly the guage behavior, I would replace it. A factory unit is only 80-90 bucks, plug and play.

I'm in the same boat as you. I get very bad gas mileage and my ecu throse a CEL which is the fuel trim malfunction code. Are there any good web sites that sell o2 sensors? The Mitsubishi dealer is very far from where I live so..

https://www.automedicsupply.com/catalog4.php?PHPSESSID=4f6ffb5a775d8d6987daee143e3 8a0aa

97gstspyder and Raginasian, how many miles per gallon are you two getting for city and highway?

i used to get great gas mileage, i probably could have gotten around 450miles to the tank or so...now a days, if i fill it up, maybe 280 - 300 if i'm lucky and stay off the boost.

Wow, I get like 250-260 :(

I only get around 150 to a tank. It really sucks and with the gas prices going up! I'll be in deep shit.

yeah gas prices here are $2.45/gal now for premium...it's never been this high here before.

yeah gas prices here are $2.45/gal now for premium...it's never been this high here before.


Premium gas (91 octane) prices where I live are from $2.59-2.89/ gallon. Be glad you don't drive in LA or SF right now. My friend told me he pays $3/gallon in LA.

I have similar problems. Get around 300 miles on a tank. Was debating on changing out the O2 sensor, but don't know if it's really gone bad. How can you tell if the O2 sensor has gone to shit? $100 is nothin to fool around with if you don't need to blow it on something like that. I get around 22-23 mpg, NON TURBO, and I don't usually drive it hard. Car is is mint shape, new plugs and wires 3k ago, good air filter (soon to be cold air intake), and I use 93 octane gas. Also threw in a bottle of injector cleaner. I love my car, but damnit why is it lacking in the MPG? Should be getting around 23 city, 33 highway. MOST of my miles are highway. (Around 75%). I can't figure it out....sorry cuz I have posted similar shit like this a few times, cuz I have no clue and this really irritates me.