In cold weather, my Honda Accord will only drive in D1, D2 or D3, not D4. However, if I let it warm up, or drive a bit in the lower D's....it works itself up to being ready for D4.

I was told this could be due to an issue with the ECM, but I sent it away to be tested for issues...and they could not find anything wrong.

More recently, my car has been going through coolant rapidly. I had a pressure test done, and there does not seem to be any leaks.

I'm starting to wonder if these issues could stem from a bad ECM (or other computer).

The car has 167,000 plus miles on it, and has recently had a new radiator, radiator fan assembly, alternator, water pump, and timing belt.

Does anyone have advice here?
Thanks in advance!!

 

EDIT**A note on the coolant issue...
My car had been overheating, and when I went to check my coolant reservoir...it was bone dry and the hose to the radiator was disconnected.
This was before getting the pressure test done, and they said it held the same pressure the hour and a half they did the test.
After taking it home, and driving it a few times, the coolant was substantially lower.

 

If the hose was loose you were loosing coolant and the system was not maintaing the correct level.
Top off coolant and monitor.

PCM will not allow transmission into D4 until the engine is sufficiently warmed up.
With low coolant the thermo sensor may not have been reading coolant temp(just air) and would have maintained the cold running parameter until the sensor was heat soaked by the head enough to register a temperature warm enough for safe D4 usage.