Perplexing problem for y'all. My friend has a 99 F-350 that has a Cold temp no start issue. This is ambient temperature, nothing to do with the engine temp. When it's above 62* out it's fine. Will start every time. Below that and no dice, once it threw the code "P1670 EF Feedback Signal Not Detected" but it has not since then, The only thing that has been changed of recent is a Water pump and a Crank Position Sensor.. Could the CPS have been faulty and when it's cold out it just not go, or a solder point in the Injection or PCM computers be fiddly in the cold weather... It ran fine last year at this time never gave an issue. Truck has 317-320,000 Miles on it... Any suggestions?

it's a 7.3L Power Stroke.

 

Sorry Wrong Section!