Hi All,
First time poster here,and I feel fortunate to be able to join such a great community!
My question pertains to the issue of a P 1299 code on my 02 f250 SD w/210k mi. As other posters have related the same set of issues,w/seemingly different resolutions I remain a bit confused. My truck was started cold and IMMEDIATELY the coolant temp guage was pegged.I shut it off turned it back on and the rough run condition and faulty guage reading ret'd to normal,and all was seemingly fine. Started it again and once again the guage was pegged -when the eng.was cold,and it again went into failsafe mode. I have read about possible cooling issues/thermostat,cyl.head temp sensors,etc,but why is this so seemingly intermittent? Does anyone know if there seems to be an electrical component to this problem? Many thanks!

 

You may want to check the wiring harness to the cylinder head temp sensor and see if it's corroded or has a loose connection.

 

Thanks for the suggestion;I will check that tomorrow. It seems as tho this problem is more prevalent in high mileage (older) vehicles,so it may indeed be a corrosion issue! Thx again!

 

Sorry for the late( to say the least!!) follow up to this original post,but I figure better late than never to post my reolution,in hopes that it may help out another...The p1299 mystery on my '02 5.4 was resolved by replacing the cyl.head temp sensor. It is a challenge to do without removing the intake manifold,but CAN be done with the aid of a wrench that one can bend to fit the tight access angle required.Patience and perseverance are key...As a brief refresher,the truck went into limp home mode even though it never truly showed any signs of actually overheating .
Again,hope this info helps...

 

Almost forgot...Thank you JH818 for pointing me in the right direction!

 

You're welcome! Glad to help.