O2 Sensors

[ylekiot1]

Trouble codes 25,26 coming up on my 90 LS400. So I am replacing my pre cat 02 sensors. Thought about replacing post cat sensors (no trouble codes triggered on those). Mechanic tells me that post cat 02 sensor failure is uncommon and that the pre cat sensors is all I should replace. Do you agree?

[92Lex]

He may find that the downstream O2S failure is uncommon but that doesnt mean they wont fail. If you're gonna change out the O2S yourself you might as well swap all of them out just for some peace of mind.

[ChrisD1]

I have a right rear o2 sensor that is malfunctioning. Apparently the heating element is not working. I was advised that the sensor still works, but not until it heats up on it's own. I am still going to replace it because a car cannot pass emmissions in Ohio with the check engine light on.

Does anyone have advice on replacing? Best place to buy, etc..

After the sensor is replaced, does the check engine light go off automatically?

Thanks for any help.

[95LS400Bob]

For 95 and up LS400's the oem's are available on Ebay for $54.95 ea.

http://cgi.ebay.com/ebaymotors/ws/eBayISAP...&category=46097

He may have the earlier ones if you contact him.

[SRK]

Use the OEM senosr only, and replace the ones that have produced a trouble code. If the post cat O2's haven't failed, don't bother replacing them.

[Lexls]

If you want to use OEM sensors that's fine, but IMO it's a waste of money. I used universal O2 sensors and replaced all 4 for a little under $150. Why did I do all 4? Mainly for peace of mind, but I was getting poor mileage....after I replaced them I noticed a big increase in fuel economy..

Main: http://www.lexls.com/mainoxygensensor.html

Sub: http://www.lexls.com/suboxygensensor.html

[92Lex]

Just curious but how many MPG is everyone getting? I'm getting an average of 20mpg or 450 a tank.

[redhawks2]

Lexls...did the codes show up on your Lexus to indicate the sensors were bad? My '90 has 124K on it but am not showing any trouble at this point. Wondering if I should keep on keeping on until they go bad or change them because of the mileage. <_<

[Lexls]

Now I'm getting about 19 MPG for all city driving, and 26 for all highway driving. Before I did the O2 sensors it was 15-16 MPG in the city and 20-22 on the highway. IMO, that is a big increase in fuel economy. In fact, the fuel economy I get now is consistent with the specs/sticker.

I didn't do any tests to see if my O2 sensors were bad, I just knew because of my mileage and the guy who I bought the car from didn't do much to it. These sensors don't last forever! You can test the main sensors while they're still in the exhause pipe. Just unplug the sensor and follow the test in my tutorial. My sensors ended up being bad.