1991LS400 Posted May 5, 2005 Share Posted May 5, 2005 Hey guys, What exactly does the Oxygen Sensor (O2 sensor) do for my 1991 LS 400? If it needs changing, how would I know? P.S. Would anyone happen to know the part number of the O2 sensor for a 91 LS 400? Quote Link to comment Share on other sites More sharing options...
blake918 Posted May 5, 2005 Share Posted May 5, 2005 You would know usually by a check engine light. Also, if your car starts to feel sluggish and/or is getting bad gas mileage, it might be time for new ones. I believe the 02's maintain the air-fuel ratio...not 100% sure though. Quote Link to comment Share on other sites More sharing options...
Lexls Posted May 5, 2005 Share Posted May 5, 2005 Yup, the O2 sensors monitor the fuel/air ratio. Usually you do get a check engine light if one goes out. However, this doesn't always happen. I had no check engine light but my main O2 sensors were out of spec......still working though. See my site for more info. Replacing all 4 sensors DID help bring my MPG back to normal range. They should be changed every 60K or so I believe, most people don't and they get a check engine light. Quote Link to comment Share on other sites More sharing options...
1991LS400 Posted May 5, 2005 Author Share Posted May 5, 2005 Yup, the O2 sensors monitor the fuel/air ratio. Usually you do get a check engine light if one goes out. However, this doesn't always happen. I had no check engine light but my main O2 sensors were out of spec......still working though. See my site for more info.Replacing all 4 sensors DID help bring my MPG back to normal range. They should be changed every 60K or so I believe, most people don't and they get a check engine light. ← There are 4 Oxygen sensors for the 1991 LS 400's? Would you or anyone else here on LOC happen to know the part #'s for the 4 sensors? Are they all the same part #, I just need 4 of them or something? PLEASE HELP! Someone's selling an O2 sensor BRAND NEW for $30 and I'm wondering if I should purchase it but I need the part number. P.S. Can I replace the 4 Oxygen sensors myself? Quote Link to comment Share on other sites More sharing options...
Econ Posted May 5, 2005 Share Posted May 5, 2005 Yeah, you can replace them yourself - lexls.com has a rockin' walkthrough, you definitely need to review it before replacing the sensors. Get an O2 sensor wrench if you can spare the $, they make things a little easier in my opinion (I got a set of 3 for $25 from the site lexls.com refers you to for sensors). Part #s for the O2 sensors: Front - 8946550010 Rear - 8946550020 Torque specs are 33 ft. lbs. Quote Link to comment Share on other sites More sharing options...
ylekiot1 Posted May 7, 2005 Share Posted May 7, 2005 I got universal sensors from oxygensensors.com and soldered the connectors from the old ones to the new ones. They also sell the ones with the connectors but for alot more $. Quote Link to comment Share on other sites More sharing options...
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