2005 Prius Code P0340 during Hot weather.

Maybe the sensor is just becoming faulty and his heat sensitive It's electronic so I guess that could be possible is the engine itself getting excessively hot no heat gauge so you might need a temperature gun or some kind of thermometer that you can shoot at different areas of the hoses and parts in the car so is the block assembly or something like that getting excessively warm I wouldn't think it would be enough to fail electronics but you never know I take it your water pump and everything is working well and all that's good?

 

Here is a step by step workup for DTC P0340 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/Prius%20Service%20Manuals%202004/%E4%BF%AE%E7%90%86%E6%89%8B%E5%86%8C/04pruisr/05/2054m/cip0340.pdf

 

I don't have a good recommendation here- the OE code diagnostic procedure assumes that you have a hard fault, not an intermittent. There are a number of possible faults that can trigger the code. Ideally, you'd have someone with a scope monitor cam AND crank sensor signals to see if something "isn't right".

The sensor itself isn't very easy to get to- info says you have to move the inverter to reach it on the back of the cylinder head.. Maybe you can check resistance (carefully backprobe) the entire cam sensor circuit from the ECM connector- but that might not tell you much. I haven't seen one of these sensors go bad (yet).