It has been a couple months now since I have fixed all my problems on the truck. The truck runs great but I keep getting this stupid P1281 code that truck is running too cold and not warming up fast enough. When I installed the new intake manifold I did put 180° thermostat on. I've replaced the thermostat back with a OE 195° thermostat. At first everything seemed to be running great and then the code comes back about every 400 to 500 miles. I do have a SCT tuner that I keep clearing the code with.

Here's the question; the Hughes F1 intake manifold did not come with a place to screw the I.A.T sensor back in it. In their instructions they said to move it to the inlet at the air cleaner which I did. Could this be causing the problem that that sensor is reading cold air for too long.

Second question; could I get a custom tune for the tuner that could eliminate this problem? My concern is that it's probably running the fuel too rich. Also when I reset the code with the tuner will it pass inspection the next time it is due? From past experience if I had a code and I cleared up by undoing the battery cables I had to run the truck for 300 to 400 miles before the computer would re-set.


Instructions;

All the lines and linkage attach and hook
up just like stock. This manifold does not have provisions for the I.A.T. sensor, which is good. The sensor should be installed in the intake air system inlet upstream from the throttle body. Normally there is enough wire to reach the intake tube. Simply cut an “X” in the tube and push the sensor in and then re‐ connect the wire. If you need an extension for the wiring harness you can order them from Caspers Electronics by calling them at
847‐247‐0484.

 

With the stock temp stat in there, and STILL getting the code.... that just seems odd. Did you get the stat from the dealer? Or, is it some cheap aftermarket unit? Does it have any holes drilled in it?

I would first suspect a bad thermostat.... not closing all the way, or opening way too soon.

 

I purchased the thermostat from the dealership. I Always test them in boiling water to make sure they're working before installing them.

 

So far as I know, that code only sets when some timer or other expires, and the engine isn't up to operating temp yet. With the stock stat, from the dealer, that shouldn't be a problem...... At least, one would think it shouldn't. Given the mileage you put on it, I doubt it is an air bubble in the cooling system either.....

Wish I had the diagnosis part of the manual........ that may shed some light on other possibilities.