Our 2002 Avalon has had a CEL for 12+ months, P1135. Car runs fine, mileage hasn't been noticeably affected and UOAs haven't indicated any issues with excess fuel. After 12+ months I decided I was tired of the CEL. Bought a Denso sensor, removed the rubber boots on the intake assembly, reached down & around with my wrench and swore and swore and swore and got no where. I soaked it in PB blaster and literally laid on the engine while reaching down/around while pushing down with my body weight. It finally broke free and turned around 1/4 turn freely then began to resist movement. I proceeded to soak with more PB blaster while managing to turn it maybe 1/8th of a turn at a time. I would loosen it some then tighten it then loosen it and continued with PB blaster soaking. I had maybe a total of 1 full turn and she wasn't moving any more. I quickly admitted defeat, tightened it back up and reassembled the intake. I have read to idle the engine for a few minutes before attempting this. Some guys even apparently use a torch to heat the manifold, I would like to see how as there is no room. Any hints/tips? I am terrified of stripping the threads and needing a new manifold. We don't have emissions testing and this is our 'beater' car so a CEL is no big deal. I am getting ready to replace the valve cover gaskets and figured I would give the ol' girl a new sensor as well. Guess not.