I have a 2001 RX300, It has 216,000 miles on it. I was getting some intermitent codes pertaining to the Knock sensors and then later I got a 1346 code for the VVT. I decided to change out the timing belt and water pump as it was due and I also changed the valve cover gaskets and spark plugs because I was there. I reassembled everything and got it running but now I have a new code that I cannot get to disappear. The P1656 code comes on when I have been running the car and I shut it off for a few minutes. When I restart, the code comes on. If I clear the code and shut the car off and restart immediately the code doesn't reappear. but if I let it set then when I start it comes back. I have replaced the OCV valve. I have checked the wiring from the valve to the computer and the wiring has good continuity with no connections to ground. I read some other forums where they thought that perhaps the timing was off. I checked the timing and as you may know the bank 1 mark is hard to see, I tried to advance the timing one tooth and retard also and ended up with a timing code of 1346. So I put the timing back and it runs good but the code keeps coming back. I have checked the screen on the OCV oil circuits and they are both clean. I am pretty frustrated as I can't seem to come up with a resolution. any help anyone can give would be appreciated.
Thank

 

p1656 means there is an electrical issue, nothing else should cause this - this code only monitors the electrical connection.

ecu, wiring or ocv

could very well be any of the above - all are sensitive to temperature and vibration