O2 Sensor replacement - 04 Sienna

I am about to change the O2 sensor (bank 1, sensor 2) on my 04 Sienna. I checked the output from all the sensors and this one is reading flat 0 volts so I know it is the correct sensor to replace. I have my O2 sensor tool (22mm) and thread chaser (just in case) and a can of PB Blaster to soak the old one. I also have a good size breaker bar. Is there any advice on removing the old sensor that people can offer based on their experiences?

If it’s rusted stuck and doesn’t want to come out, try some heat. Mapp gas works fine. Hit the area around the threads for 10-20 seconds and you’ll be amazed at how easily it will turn.

@JoeMario - Thanks. I am hopeful that it is not too stubborn. The exhaust was replaced a year ago so the sensor would have been taken out and put back into the new exhaust at that time. I guess I won’t really know until I put the wrench on it.

Are you replacing it based on a fault code and/or check engine light?

P0037 code (and the CEL is on). I have a real time diagnostic tool and, with the engine running, I can see the output from all four sensors. The only one with a zero voltage readout is the sensor in bank 1, sensor 2. The P0037 reads “heated O2 sensor low voltage bank 1, sensor 2”.

If you replaced the exhaust already it should be super-easy. I’ve replaced 3 of the 4 on my '04 truck (from a rust belt state) for bad heaters. I used a combination wrench. PB blaster on a cold pipe. Cut off the wire pigtail and slipped on the 12-point end and whacked it with a hammer a few time to break it loose and off it comes. I love stainless steel… even the cheap stuff!

Thanks @Mustangman.

Nobody else has any suggestions? Maybe I should say something inflammatory like “I think 10,000 mile oil changes are awesome”.

I heard “Keeping your mind full and you’re bowels empty” is sound advice.

I’ve found that if the old one is seized too bad, you can cut the wires off short at the sensor and use a good deep well impact socket until it’s broke free. Sometimes those sensor sockets with the slit up the side are just too flexible and slip right over to the next lands.


** Update ** I was able to replace the O2 sensor in about 20 minutes. The old one turned immediately without heat or penetrating oil so it was a snap to remove. The new one popped right in and was easy to connect to the harness inside the van. I fired up the engine, cleared the code and CEL, and watched the output from all of the sensors on my scan tool. Everything looked good so I buttoned it up and have been driving it for the last four days and 500 miles with no return of the CEL. $57 in parts and $15 in tools versus paying the dealer over $200. I am pretty happy and have a little more money in the vacation fund for the summer.

Congratulations bloody_knuckles on your success. Finding the real fault and correcting it is the only way too go.

I used the crowfoot style wrench but had to use a 8" ratchet extension. Of course the end result was a “U” shaped mess and the end of the extension sheared off.

There you have it… another job well done. The right tools save the day all the time… Good Job