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Q: Can not pass emissions on 1996 Lexus LX450

I have failed my emissions now 4 times. 1st time battery was dead from sitting, replaced battery then check engine light came on it failed stating needed to wait for computer to reset & to drive for 2 weeks. Went back 2 weeks later it failed stating O2 censor, replaced it went back then it stated the computer needed to reset again,. drove it for 2 weeks now its showing the lower O2 Censor... What the hell? What do I do?Why is this showing up now?
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The computer is registering some type of fault, which may or may not be the O2 Sensor. Do you know the diagnostic codes that they have pulled from the engine computer? With that info I can better help you.
O2 Censors do go out ocasionally. I had that problem also I ended up replacing my Catalytic Converter because it was getting clogged and not burning off the exhaust gasses like it should. Catalytic Converter will sometimes foul out the O2 Censors. If I were you I would buy 4 cans of SEA FOAM engine treatment and pour one can per tankfull. drive it for a Month and see if that solves your problem. If you don't have time to drive it for a month just you may need to replace your Catalytic Converter with a new one. If You have been filling up with regular fuel for years and you have never used an engine treatment like Sea Foam that is probably why your Converter is getting clogged. If you only drive short trips to work or wherever you go the converter does not have time to Heat Up this diminishes the life of the Catalytic Converter. The Converter needs to be able to Heat Up to it's Maximum to be able to clean itself out and burn Up the exhaust fumes so that you can pass emessions test. Try driving your Car for about 30 to 40 miles before you drive up for your emissions test also use the SEA Foam treatment in your Tank of Gas. Leave your Car running while you are in line for your Emissions Test don't kill it and allow it to get cold. Wait until the weather gets warm like in the summer time this may help your converter to get to it's Maximum Heat range. Good Luck
Did the last test only fail due to high CO2 levels? Were your carbon levels too high? My car failed with high CO2 levels. Not the check engine lights, not service engine lights, just the carbon. My local auto shops only wanted to charge me an arm and a leg to fix nothing! A friend of mine used an emission fuel additive and I was skeptical but I tried it and it worked. I had to use it on an empty tank and treated the fuel, then tested the car when I was close to E again and viola! It passed. At this point, it may be worth a try if your CO2 levels are too high. The company is Sorry this is so frustrating. Best of luck!
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