I have a Honda Accord V6 2001 model. It has electronic problem in cold weather. Car starts normally but half the electronics do not respond. Especially, the TCS switch does not respond and car does not engage in Drive (no gear engage and no D light on dashboard). All other gears engage (D1, D2, D3 etc.).

Once the car heats up. I have to restart and things work normally. I lived with the problem for one winter and then next winter my check lights starting getting on. The code is ECU Failure. However, once the car is fully heated and I restart it check light might go away. In the summer, car works perfectly fine.

Now the temperature at which I see this problem is getting higher an higher. At first the problem was at around 32F and below. But now I see problem at around 40F as well.

Honda dealer says it is CPM failure. But it could be also transmission failure. My gut feel and research says it could be O1 or O2 sensor failures. My point is ECU is a computer and how could it start working in warmer temperature.

Each of the repair (CPM replacement and O1/O2 sensors replacements) are about $800. I am confused which one I should try first.

Any guidance here would be really helpful.

As any printed circuit board goes through what is called "thermal cycling" it can twist and expand resulting with intermittent open circuits within the control circuits on the board.
This can happen to any vehicle regardless of year, make, model, location, driving habits, etc.
The only way to confirm the diagnosis would be to monitor as many operational parameters both before and during the onset of the symptoms as you've described.

Disconnect the negative. Battery cable and the connector going to the PCM. Spray the connector with WD-40 and see if the problem goes away. If not, try substituting a known good PCM and see if it solves the problem. I don't believe it has anything to do with oxygen sensors.

Thanks. Taking out O2 sensor heater out of questions helps resolve my doubts a lot.