Cold start

I need some help. I have a 2001 f-250, 7.3 with 275,000 miles , sct tuner, afe cold air intake and 4" exhaust from the turbo back. Truck runs great and never gives any problems ...until it gets real cold! Last year if it dropped below 25 degrees the truck would not crank and kept throwing codes 1670 and I think 603, 1670 is the one that I'm most worried about "electronic feedback signal not detected". This year in the last couple months I've had the glow plugs changed and I personally changed the glow plug relay, I know the relay is working and I'm getting power going in to the valve covers but if I do not plug my truck in it will not crank at temp. below 32 ish , and it throws the 1670 code even when I clear it and try to crank it it will throw it again. The truck just spins over and I get no exhaust coming out the pipe. Any help with this matter would be greatly appreciated as I'm about to loose my mind ..lol. Thanks!

Check your UVC harnesses. If those are original injectors in there they could be getting very tired at that mileage.


Sent from my truck while eating, adjusting the radio and passing a Mustang sideways.

And check your batteries.

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As far as I know they are the original injectors and both batteries are good, like I said truck runs great until it gets really cold outside and then once I get it cranked it runs like a champ!

what oil are you running and how long do you plug it in before you try to start it? not that either of those have anything to do with the code though.....

live life full throttle

Rotella 15-40, if I plug it in at night it will crank right up so far this year there was a couple times last year when it got into the teens where it wouldn't crank even plugged in. Today I purposely left it unplugged last night, went out this morning , just spins over , checked and made sure my glow plug relay was working and it was, still throwing code 1670 and 603, tried cycling the glow plugs half a dozen times or so still nothing, plugged my sct programmer in cleared the codes and it fired up?????

get the rotella out of that engine and put delo 15-40 in it... rotella is the oil i had the most issues with on cold starts...

when you get it running and its up to operating temps what is your battery/alternator voltage? what is your voltage before you even cycle the key on to try to start it in the mornings? does it ever throw those codes when its at operating temps?

live life full throttle