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.

 

Check this post for the tools ... Recommend half inch drive... soak in solvent 12 hours prior.

https://www.clublexus.com/forums/sho...d.php?t=227715

I personally like the Blue Point socket...

 

I had cousins go to Iraq in the Illinois National Guard and it was a very difficult experience for them, and that is an understatement. I know all of our hopes and prayers are behind you. Whatever support we can give at ClubLexus, you have it.

OK. Bank 1 sensor 2 right after your main catalytic converter. I don't necessarily think it is dead. There is also a P0420 error for underefficient catalytic converter and that should also pop off.

I have had a misfire and a bad ignition coil last December, but no problem with my converter as I have checked it on gas analyzer at my exhaust shop several times since, and if there is a place you could have it analyzed that would be a good way to do it.

The only trouble area listed for the P0136 error is the O2 sensor, though the wiring harness might also be suspect.

The O2 sensors can and will go as many of our fellow RX300 CL members have found out. There is no one reason in particular that it happens.

I know a few of the other members here are experts on rusted bolts, so I am sure they will chime in shortly.

 

Guys, thanks for the help. I got one of the nuts off but the other one sheered off as I was taking it off. I guess my O2 sensor will be held on with only one nut. Thanks,Ryan