rreuth

There are lots of posts on this CEL coming up along with the VSC light. The code that is found (P0135) normally seems to point to the Bank 1 Sensor 1 oxygen heater circuit. But, as you note, it can be expensive and/or difficult for the DIYers to replace that sensor. I am having the same problem with a 2003 RX300 with just over 100K miles. I have cleared the codes many times, but it will return after a short time. Short time appears to be anything between 10 and 500 miles. I did clean the MAF, checked the vacuum air line on the back of the air cleaner box, and replaced the Bank 1 Sensor 2 oxygen sensor heater, but the CEL and VSC lights return. I cleared the code (again), and I am now using a Tier II gasoline exclusively. I have been using it for about 1000 miles (3+ tanks). The lights have not come back on. I have my fingers crossed. I don't know exactly how to explain why the Tier II gas seems to be working, but I would note that I also have a 2002 Corvette. The fuel gauge would go to zero after getting to between 1/2 and 1/4 of a tank. This would cause the low fuel warning lights to come on and force me to fill it with gas quickly (either that, or try to manage the fuel by following the odometer readings). On a Corvette forum, I came across a post noting that the problem was believed to be caused by using a non-Tier II gasoline. After awhile, the non-Tier II gas would corrode the surface of the fuel gauge sensor in the fuel tank. Using a Tier II gasoline (and trying to use Chevron or Texaco with Techron in it) caused the problem to go away. Putting some tanks of a non-Tier gas back in would cause the problem to reappear. Would be interested in hearing about similar experiences!