How hard is it to DIY replace an O2 Sensor?

[evident]

I have a 2007 Lexus RX350 with about 90K miles. the OBDII error code P0037 set off the check engine light which indicates " Oxygen Sensor Heater Control Circuit Low (Bank 1, Sensor 2)" which from my research indicates is the down stream sensor.

How hard is it to DIY an O2 sensor replacement? Are there any tricks I need to look out for? I haven't found youtube or DIY instructions for my specific vehicle (or toyota highlander). How likely is it for O2 sensors to be in a hard to access spot? I have jack stands and all but i'm not willing to disconnect a ton of stuff to get to get to a sensor. (I know on these cars and this 2GR-FE engine you basically have to take off the intake manifold and a bunch of other parts to replace the 3 spark plugs closest to the firewall. if and when the time comes for that i'm just going to take it to a Toyota dealership. that's too much hassle to save $100 bucks). Also, is it necessary or ideal to replace the upstream sensor when replacing the downstream? If they are both in roughly the same spot I might as well do both at the same time. They are expensive though. $180 for an OEM replacement.

edit: actually I found them for $70 for a OEM denso replacement. but are they worth replacing in pairs? i'm getting mixed messages about O2 sensors in general when researching online. the upstream sensor for bank 1 on this car is in the pain in the ass spot to get to, so i'm going not even going to bother, unless if when i replace the downstream it trips the upstream check engine light for some reason.


UPDATE: I did this job in an hour. I was very fortunate that the crapped out O2 sensor was the one that was directly under the car. I did NOT need to jack the car up. i slid right in from under the drivers side door and had plenty of clearance to work with.
the new O2 sensor was a drop in replacement, exact same wire length and with all of the clips in the exact spots they needed to be. Everything clipped right in. at first the old O2 sensor wouldnt budge, but I sprayed PB blaster on it, waited 15 minutes and was able to brace myself against the front driver side tire and kick the wrench with my foot.

reset the obd ii code with my 12 year old scangauge and it hasn't come back on since!

I probably saved at least $300, since the part at toyota cost $250, and add labor on top of that would have probably been another $150. I was able to get the exact same denso oem sensor on rock auto for 80 bucks.

 

[Jadow]

as long as the car is driving smooth, not worth it. also no idea how hard

 

[shabby]

How likely is it for O2 sensors to be in a hard to access spot?

Since its a lexus... its almost a dead give away you'll have to remove the engine to access it.
Just look for it along the exhaust and see if you find it, then see if you can get a wrench around it or you'll need a o2 sensor socket that has a cut in it to remove it.

 

[pauldun170]

Get the car up on jackstands and judge for yourself.
Looks fairly straightforward.

B1S1 - bank 1, sensor 1, before the cat on bank 1
B1S2 - bank 1, sensor 2, after the cat on bank 1

B2S1 - bank 2, sensor 1, before the cat on bank 2
B2S2 - bank 2, sensor 2, after the cat on bank 2

Read more: http://www.clublexus.com/forums/rx-...-p2195-for-bank1-o2-sensor.html#ixzz38uvNMSfE
​

Note - Pic below is to give general idea where to find them. Its obviously not pic of RX350 manifold

 

[pauldun170]

Here are the locations
http://lexus.sewellparts.com/oem-catalog/8401847668-Electrical-RX350-2007.html

 

[thedarkwolf]

They can be a huge pita if they are really stuck. The o2 sockets are great for installing them but not always so great for getting them out. The slot in the socket to clear the wire makes the socket weak and flexy. If they are really stuck I take a hammer to them and break off the pigtail part(wires and extra crap) and put a regular 6 point socket on it. On my old mustang I had to break down and take the exhaust off so I could get an impact gun on the damn things.

 

[Hartle4]

I work on cars all day long, and trust me they can be very difficult to remove.
just cut the wire right at the sensor and use a regular socket to remove it, the sensor socket probably wont work. Also about %50 of the time i have to use heat/torch to remove old ones. Being that your car isnt even ten years old though you could probably get it out, unless you are in a rust state

 

[DaTT]

Does that o2 sensor play any major role in the tune of the car?

I had my catalyst monitor keep throwing codes due to having high flow cats, had my tuner shut that sensor off. It doesn't play any role other than observation though.

 

[Jimzz]

That one should not be hard but just jack the car up and see where its at and if its free around it.

On my truck the driver side front is not to bad but the pass requires removing the tire, inner fender. and then you can kinda get to the cramped sensor.
And on many 4cyl cars its right there in front of you.

Advance auto and AZ have the O2 sockets in their rent a tool. Just need a 1/2" ratchet to use them.

 

[evident]

Took a look underneath the car this morning before going to work. I think I was able to see what I believe was bank 1 sensor 2 according to the diagrams. Didn't see where the wires went to though. the exhaust pipe is kind of aligned towards the passenger side, so I bet the wires will pop in somewhere in the center console on the passenger side.
The O2 sensor itself looks like it's in a pretty easy to access location. I might just set up my go pro and do a DIY vid when I actually do it since I don't see many videos on this engine/car...

To those who are saying it's not worth it, what do you mean? won't it screw with the catalytic converter and fuel mix over time if i leave it as is? I also hate driving with check engine lights on. it's annoying and could mask other issues. Also, is it worth it to replace the upstream while i'm messing around with the car?

 

[njmodi]

1. No need to replace in pairs.

2. The O2 sensors upstream from the catalytic converter do impact your fuel trim - so I would recommend replacement. In some states, you can't pass smog/emissions testing with the CEL on anyway - so in that case you don't have a choice. Especially if the issue is chronic and keeps setting the CEL.

3. It's actually a "simple" job - but can be difficult to get the leverage you need to break the old one free. Simple in that, disconnect old one, unscrew it, replace with new and connect it and you're done. You typically don't have to to remove any other fasteners, accessories, etc.

4. Make sure the OEM Denso includes the correct connector... you can also buy replacement O2 sensors that don't include a connector - they have a wire pigtail, and you are supposed to splice in the connector from the existing O2 sensor.

5. Spray your favorite penetrant onto the O2 sensor threads and let that soak, and that will help.

6. You need to figure out where the connector is (as you have already mentioned). Typically the wire will run up into the engine bay and connect into the main harness inside the engine bay itself. An exception will be the rear O2 (post catalytic) sensor - which does connect into the harness inside the car.

It's really not that hard - just can be awkward angles, and difficult to get the leverage to break the old one loose. Once it's loose, it's smooth sailing from there.

Cheers and good luck. Post a link to the video if you do put one together.

 

[sontakke]

No, the rear sensor (the one AFTER catalytic converter) does not (usually) affect your mixture. It is only there to measure your emissions and to make sure the catalytic converter is working efficiently. For example, if your catalytic converter is marginal, AND you do replace this rear sensor, then you might end up with P0420 code afterwards!

 

[njmodi]

No, the rear sensor (the one AFTER catalytic converter) does not (usually) affect your mixture. It is only there to measure your emissions and to make sure the catalytic converter is working efficiently. For example, if your catalytic converter is marginal, AND you do replace this rear sensor, then you might end up with P0420 code afterwards!

Yes you are absolutely correct. The post-catalytic O2 sensor does not affect fuel trim. I was referring to the sensor the OP said is being reported as failed - I have clarified.

 

[Fritzo]

O2 sensor failures are almost always the pre-cat (not post cat). These are usually fairly easy to get to, and you can remove them about the same way as a spark plug. From the diagram above, it looks like the pre-cats are pretty accessible. Be sure to borrow an O2 sensor socket from your local autoparts store so you don't damage the wires.

I was able to change the sensors in my BMW in about 15 minutes, and the rear one was a bit difficult to get to. A ratchet with a long adapter was helpful.

 

[evident]

UPDATE: I did this job in an hour. I was very fortunate that the crapped out O2 sensor was the one that was directly under the car. I did NOT need to jack the car up. i slid right in from under the drivers side door and had plenty of clearance to work with.
the new O2 sensor was a drop in replacement, exact same wire length and with all of the clips in the exact spots they needed to be. Everything clipped right in. at first the old O2 sensor wouldnt budge, but I sprayed PB blaster on it, waited 15 minutes and was able to brace myself against the front driver side tire and kick the wrench with my foot.

I probably saved at least $300, since the part at toyota cost $250, and add labor on top of that would have probably been another $150. I was able to get the exact same denso oem sensor on rock auto for 80 bucks.

 

[njmodi]

:thumbsup: Thanks for reporting back. Glad it worked out for you.

 

[IGemini]

Glad you had better luck than I did, had a similar experience on my 2005 Impala this past month. Even after soaking the sensor in PB blaster for a week it wouldn't give. Brought it to a garage to get it loose, they were pretty surprised it was on that tight. Labor cost about as much as a breaker bar so it wasn't too bad.

Really annoying location for the O2 sensor as well, it's on the top of a U-joint pointed into the car's underside, it requires using a wrench with a flexible head. Only one year shy of GM putting it in a more accessible location. :hmm:

$250 for a sensor? Even for Lexus that sounds ridiculous. Advance had some nice online coupons at the time, got my Denso for $50.

 

[evident]

http://lexus.sewellparts.com/accessories-catalog/acc/GS350-2007/5813.html

I know it's for a GS350 but it was the first thing i googled. sewell is the cheapest when it comes to online parts providers from dealers. the denso from rockauto was the exact same length, same clips in the exact same places and everything, for $80. the only thing that was different was that it didn't say "toyota" on the o2 sensor itself. i'll post pictures later this evening but since this isn't a rx350 specific website im not sure how much it's going to benefit anyone here.