DIY: front O2 sensor on 02 WRX

[WRXreX]

Spent about 30 min installing front O2 sensor on my 02 WRX sedan.

Tools you need:

Wretchet
10mm and 12 mm sockets
22mm O2 sensor removal tool ($9.99 from autozone)
Two zip ties unless you know ways to remove crappy zip ties from the bracket.
New Denso O2 sensor (~$150-160)

Please note that I am going to skip many basic stuff such as removing wheel, bolts, etc...

1. FR wheel removed:


2. Locate this mudguard and proceed to remove it to expose O2 sensor.


3. Remove O2 sensor using 22mm special removal tool


4. Locate harness located near boost control solenoid and disconnect it


5. Take this bold off, which will free up the bracket attached to the O2 sensor wire. There are two plastic clips that hold O2 sensor wire. If you have changed spark plugs, you may have wondered what the purpose of this bracket is...


6. Proceed to remove O2 sensor and bracket/harness from the bottom. O2 sensor shown here (new vs. old).


Now, put everything back in reverse order. Now, think about what to do with $200+ you saved by doing it yourself.

[king3style]

Please help. I need to loosen the bracket as shown in picture 5 to create slack for the wires. However, I don't see how to get to picture 5? How do I get access to the engine harness to unscrew that bracket? Do you go from the top? What do I have to remove to get at it? Plus the wire looks like it is clipped in twice on that bracket. How do I remove the clips? I cannot reach in there at all.

Thanks for the help.

[WRXreX]

Please help. I need to loosen the bracket as shown in picture 5 to create slack for the wires. However, I don't see how to get to picture 5? How do I get access to the engine harness to unscrew that bracket? Do you go from the top? What do I have to remove to get at it? Plus the wire looks like it is clipped in twice on that bracket. How do I remove the clips? I cannot reach in there at all.

Thanks for the help.

You will need to remove intake box in order to reach there. It's pretty simple to do. Just use zip-ties to secure wires.

[king3style]

The computer says the problem is Heat Sensor Bank 1. I am guessing that this is the front 02 sensor. If I replace it should/will the Check Engine light go off.

[cheezycow]

Yes your cel should go out after 3 driving cycles or if you do a reset. Oh and the bracket does not have to be removed just crimp the tabs with needle-nose pliers and push them through. The new sensor should come hopefully come with the replacement tabs already in place.


great useful write-up btw

[grizzle]

I think I need to do this. I am getting P0032 and P0136. 02 sedan. Anyone know the 02 sensor part number?

[cheezycow]

22641AA042 should work for you

[F20c1]

Hi, thanks for the guide. It is goning to be very helpful when I change my sensor. I have one question that might be kind of stupid. What is that tube of copper colored paste for? I also got one when I bought a new sensor but don't know what it's for.

[doginarocket]

Hi, thanks for the guide. It is goning to be very helpful when I change my sensor. I have one question that might be kind of stupid. What is that tube of copper colored paste for? I also got one when I bought a new sensor but don't know what it's for.

Not a stupid question - It's the anti-seize compound for the sensor's threads.

[Fran]

So I picked up a standard oxygen sensor tool last night at O'Reilly. Measures 22mm exactly:


I got up this morning and went to town trying to get the old sensor out of there. I was feeling good about it until I realized I hadn't been turning the old sensor at all, but stripping the nut instead:


3 questions?
-What went wrong?
-How do I fix it?
-If I'm going to drive (<2 mi.) to the Subaru shop, will I need to reroute the old sensor wire and reconnect it or can I just snip it and go?

[Erad99]

So I picked up a standard oxygen sensor tool last night at O'Reilly. Measures 22mm exactly:


I got up this morning and went to town trying to get the old sensor out of there. I was feeling good about it until I realized I hadn't been turning the old sensor at all, but stripping the nut instead:


3 questions?
-What went wrong?
-How do I fix it?
-If I'm going to drive (<2 mi.) to the Subaru shop, will I need to reroute the old sensor wire and reconnect it or can I just snip it and go?

Been a month plus since you posted, I'm certain you are not sitting waiting for a response still. As I'm researching the steps for my own removal/replacement, thought I would respond to your questions with my shade tree mechanic experience.

1) Those open sided tools do not have the same grip as a crow foot type O2 removal tool. I have one like yours and have used it successfully without stripping the old sensor though..So can only assume you may have had it on just the tip and began stripping it as you went along.. Question to you is did you do this by hand or did you use an impact gun ? If by impact, that may be your issue.

2)Fix it ? maybe bring the engine up to termperature and try with some vice grips or other locking pliers or other tools. once rounded that may be tough to remove. There are rounded/rusted bolt removing ratcheting wrenches that will permanently mess up your bolt by gouging into it..but it will remove it.

3) As we are assuming you are having O2 sensor issues to begin with, your sensor is already likely blown or fouled and causing issues. snip the wire or drive to the dealer/shop as is. Don't boost high if you can help it, but ECU is likely already in limp mode and using reserved A/F ratios.

[Fran]

I did it by hand. It's in kind of a tight spot so once I had the removal tool on there I couldn't really see what was going on. My guess is it shifted a bit as I cranked down and I had rounded the thing off before I knew it. I took it over to my mechanic and he advised me to just pull the exhaust manifold and take it in to a machine shop. He said chances are it's rusted in there pretty good if it was that hard to get out, and I'd run the risk of cracking the exhaust if I put the kind of force on it that it'd take to actually remove it. I could probably poke around a junkyard for a decent one but I don't have that kind of time.
Long story short, it's just been sitting in my garage for the past few weeks. I have the exhaust all but removed at this point, just a few more tricky bolts to go. I'll post again once I take it to a machine shop.

[Erad99]

I did it by hand. It's in kind of a tight spot so once I had the removal tool on there I couldn't really see what was going on. My guess is it shifted a bit as I cranked down and I had rounded the thing off before I knew it. I took it over to my mechanic and he advised me to just pull the exhaust manifold and take it in to a machine shop. He said chances are it's rusted in there pretty good if it was that hard to get out, and I'd run the risk of cracking the exhaust if I put the kind of force on it that it'd take to actually remove it. I could probably poke around a junkyard for a decent one but I don't have that kind of time.
Long story short, it's just been sitting in my garage for the past few weeks. I have the exhaust all but removed at this point, just a few more tricky bolts to go. I'll post again once I take it to a machine shop.

Shame to have your vehicle sitting and I can sympathize. My WRX was on jackstands a better part of the late summer for lack of parts/slow delivery.

One thing you can look into is getting yourself a recycled part as you mentioned from a yard or buy yourself an inexpensive Ebay header (100$ range!!) and new O2..I'm assuming you already have the O2 sensor for having began the removal. Alternative is just look on other sites for part outs, you might get lucky and get yourself one with the sensor for dirt cheap.

Best of luck to you.