my 2003 s type 3.0 has fault code 1549 which as far as I can tell is intake air control solenoid upper, the problem is when the outside air temp is 20 degrees or below the engine is hard to fire up and sounds like it is running on 3 or 4 cylinders I can keep it running for a few minutes and turn it off and restart it, it will run normally until it is shut off and cools to ambient temp again, I can find little information on code 1549 how to find or repair the solenoid or if this is causing the problem.

 

There's no 1549. All codes have a letter.

 

sorry that was supp-osed to be p1549

 

It's a IMT valve fault. (The bottom one)

I'd suspect the wiring first, it gets pretty hot back there, you can buy pigtail kits from the Ford catalouge to replace the plug if there is a break nearby.

 

Judging by the low number of search hits, P1549 is not a very common fault.

Can't remember, are the two IMT valves interchangeable? If so, you could swap them for troubleshooting and see if the fault follows.

Don't forget to get the upgraded (green) O-rings for installation. The old ones tend to break down and are a known problem area, causing vacuum leaks and lean fault codes.

 

Yes, the two IMT valves are indeed interchangeable....

 

The previous posts about P1549 look worth reading.

 

https://www.jaguarforums.com/forum/s-type-s-type-r-supercharged-v8-x200-15/p-1549-imt-question-86633/