I've gotten PM's of people on this forum telling me a bad 02 sensor can be causing bad gas mileage, bad idle, and just flat out run the car ****tty - that's exactly all 3 things I'm getting.

I appreciate the help I'm getting from those people.


1st question how much will it cost me to replace 02 sensor? (part+labor)

I already know how to make sure it's bad or not thanks to malibujack.

2nd question What caused my 02 sensor to go?.. 16,000 miles on the car, no racing, no drag, just modifying the hell out of it. I don't use race gas so that can't be it. I just don't want this happening again so I'm trying to find ways to possibly protect it.

It seems the CEL I got for the 02 sensor came right after... cam shafts install w/ arp head bolts + fuel pump and a custom flash also time on the dyno if that affects anything... they were all done by well known experienced Evo professionals so I don't think they did anything wrong but everyone makes mistakes...

 

$ 300.....shop total. I wouldn't pay for more. There are aftermrkt companies that sell the same O2 for less money. Just have to search.

Find a friend that knows what he's doing....case of Man fuel.

 

sounds good.. that's not as bad of a price.. I figured it was going to be around $500.

any idea on the cause of the problem or ways to prevent it from happening again.

 

Just to let you know. O2 sensors are warrantied for 8 yr/80 K miles. Why do you want to pay for this work?

Don't know for sure why they go bad ...They just do. Whether be it 500 miles or 100K.

I think A/F's plays a good role on how O2 sensors last.

 

that would great if they warrantied that... but if you look at the list of my mods.. I really don't feel like a hassle with Mitsu to get it done... I'm pretty sure I voided all my warranty out.

There's only 3 Mitsu dealers left in my state btw... all in inconvenient locations for me.. I'm hoping I can calll them Monday and have them ship it to me.

 

O2 sensors can be killed by using sealants that aren't O2 sensor safe. A shop would have to be pretty delinquent to do this, but it could happen. It's also possible that you have a problem with the wire to the sensor and that the sensor itself is okay (though the wire comes with the sensor if you replace it). This could happen through negligence when your cams were put in (they had to disconnect the wiring for the O2 sensor then). The car would have to be running crazy rich for a prolonged period to hurt the sensor though. I think it's more likely that it was damaged in some other install.

 

damn dude.. nice explanation it was a very well known Evo shop to install my cams.. and my local shop did mention that about unplugging the 02 sensor when installing cams.

thanks for all the help guys... maybe after all this hassle I'll have my car running again with a new 02 sensor... can any of you guys list any websites I could order this?

I searched google found various Mitsu OEM parts websites but they don't sell 02 sensors. I wouldn't mind settling for an aftermarket sensor if the price is reasonable and durability is as good as OEM.

Thanks

 

You could try www.oxygensensors.com They're pretty cheap there.

 

You might want to double check that the oxgen sensor harness is securely plugged in under the spark plug cover. If you remove the plastic spark plug wire cover with the Mitsubishi logo (4 bolts that can be removed with a phillips screwdriver and you might need to unclip the throttle cable and pull it aside to get that cover off) you'll see the O2 sensor wire coming up from the front left hand side of the motor that disappears under that cover. The end of the O2 harness is bolted down under there and there is a plug that snaps into the wiring harness that comes from the behind the motor. The connection is under that cover. If it weren't fastened correctly (it snaps), then the O2 sensor might act dead. You'd get a CEL light for sure if this were the case. If your car has been acting up since you got the cams, this could be worth checking. You might also just inspect that wire for as far as you can see it going down to the O2 housing below the turbo to see if it looks burnt or anything. This all might be a long shot, but it can't hurt to check if you have a few tools.

 

Oxygen Sensor MN153010

Oxygen Sensor
MR578532 fits prod date upto 08/03
MN191125 fits pro date after 09/03

I don't know which of these is the front O2 and which is the rear, but here are some part numbers for the Evo O2 sensors. You can get them from Rockville Mitsu for a decent price. They are local to us here, but they work through the mail to. They are at mitsupartsdirect.com and have been very professional on the phones when I've dealt with them. Click on the Evo Club link for the list of common part numbers.

 

great! thanks so much... I hate troubleshooting cars but I'll make sure I have print out of all the reply's and test everything.

I'll let you all know how it worked out

 

The site doesn't have any sensors for 04 Mitsubishi's.. but it's ok.. I may just ask the dealer to ship me one

Thanks

 

if you can't replace an o2 sensor yourself, you shouldnt own an evo.

 

Thanks I don't need someone to tell me what I can or can't own. If I work to pay for it I can own it.

I'm in a completely different field from cars.. I just enjoy to have a nice fast turbo car.

 

I didn't see where anybody mentioned your use of an aftermarket cat.Many have the same problem you are experiencing resulting from aftermarket cats or delete pipes.Use your stock cat and reset your ecu and see if the results are the same.