Atroop Posted July 30, 2006 Share Posted July 30, 2006 Hello All, I am in need of some good advise on a problem I'm having with my '99 RX300, 93,000 miles. A while back my RX was running like crap and I was getting a flashing check engine light. The codes I was getting were bank 1 random misfire and bank 1 running lean. After about a month of troubleshooting, I finally figured out that it was the Bank 1, O2 Sensor #1 (air/fuel sensor). The sensor was bad and it was giving a false lean reading to the engine, causing the injectors to shoot too much fuel into the cylinders and thus causing misfires. I replaced the sensor and since then the car has been running great. After replacing the Bank 1, O2 Sensor #1, I started to get another check engine light reading P0136 (Bank 1, O2 Sensor #2), although the car is still running good. My question is in regards to what could be causing this as I've heard that this sensor should last for 200,000+ miles. Could my catalytic converter have been damaged when I was getting random misfires and the false lean reading by shooting hot fuel into the cat? Or could the sensor be legitimatly bad? I bought a new sensor but the old nuts are so rusted on that I can't get them off. If I cut the bolts I won't be able to get the new senor on. Any advise is greatly appreciated! Ryan PS - I'm in the Army and leaving for Iraq in two weeks and want this fixed for my wife before I leave. Quote Link to comment Share on other sites More sharing options...
chubyball Posted July 30, 2006 Share Posted July 30, 2006 Hello All, I am in need of some good advise on a problem I'm having with my '99 RX300, 93,000 miles. A while back my RX was running like crap and I was getting a flashing check engine light. The codes I was getting were bank 1 random misfire and bank 1 running lean. After about a month of troubleshooting, I finally figured out that it was the Bank 1, O2 Sensor #1 (air/fuel sensor). The sensor was bad and it was giving a false lean reading to the engine, causing the injectors to shoot too much fuel into the cylinders and thus causing misfires. I replaced the sensor and since then the car has been running great. After replacing the Bank 1, O2 Sensor #1, I started to get another check engine light reading P0136 (Bank 1, O2 Sensor #2), although the car is still running good. My question is in regards to what could be causing this as I've heard that this sensor should last for 200,000+ miles. Could my catalytic converter have been damaged when I was getting random misfires and the false lean reading by shooting hot fuel into the cat? Or could the sensor be legitimatly bad? I bought a new sensor but the old nuts are so rusted on that I can't get them off. If I cut the bolts I won't be able to get the new senor on. Any advise is greatly appreciated! Ryan PS - I'm in the Army and leaving for Iraq in two weeks and want this fixed for my wife before I leave. I had the same problem I did swap the sensor left to right and right to left to see the damn codes changed, but after replaced both catalitics cost me a fortune, I end up replace the second cat with after market part with cost of $300.00 and the code still there. Finally I replace both send sensors after the cats. Now the Engine code went a way, it has not came back since. My suggestion to you is replaced both of them and reset your computer. Remember to buy Denso parts, you can purchase from the website, it's a little cheaper from dealer about $20.00 for each. By the way, my sensor went bad at 115K miles, not at 200k Quote Link to comment Share on other sites More sharing options...
lenore Posted July 30, 2006 Share Posted July 30, 2006 Ok I am confused, You changed both Oxygen sensors on the engine or did you replace the sensor down on the Catalytic converter. I believe there are a total of three sensors on the RX300?????? Two on the exhaust manifolds and one down by the Catalytic converter. Quote Link to comment Share on other sites More sharing options...
chubyball Posted July 30, 2006 Share Posted July 30, 2006 Ok I am confused, You changed both Oxygen sensors on the engine or did you replace the sensor down on the Catalytic converter. I believe there are a total of three sensors on the RX300?????? Two on the exhaust manifolds and one down by the Catalytic converter. How many cats do you have? I have a LS400 95 and it has 2 cats total of 4 Oxygen sensors, 2 before the cats (locates between manifold and cats) and 2 after the cats (locates between the cats and muffler pipe). I replace the 2 after the cats. Quote Link to comment Share on other sites More sharing options...
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