Difficult to Start Engine? Replace the CHT (Cylinder Head Temp Sensor)
I battled a difficult starting problem with my E150 recently. My van would take 10 or more times of attempting to start it before it would actually idle. It would stumble and almost start many times. Once it started it would easily start again without issue. If I let it sit overnight it would have the same issue in the morning. It seemed time or engine temperature related. Many people told me it was my fuel pump, Fuel pressure regulator or fuel filter. Yet, a key-on-key-off testing situation proved to me that it was not a fuel pressure issue.
My issue turned out to be the Cylinder Head Temperature Sensor (CHT). Although I only got the error code P1289 once after many times of clearing the codes and driving more, that's the one that eventually lead me to this sensor. P1289 is "Cylinder Head Temp Sensor High Input". I learned through plenty of troubleshooting and searching that the dash cluster temp gauge gets it's signal from the coolant temp sensor on the thermostat housing. The computer gets it's signal from the CHT. My CHT was malfunctioning and was causing the engine to never start properly. It would take 10+ times to start it properly. The CHT sensor itself is a dealer only part. It was $23 dollars from a local Ford Dealer part number XL3Z 6G004 AA (XL3Z-6G004-AA). When I got back to replace it, I snapped the old one off inside the head. No biggie, because there are about 3+ other tapped holes in the head to screw the new one into. I used a different hole and the engine started on the first shot. This was a really easy job because this was a E150 van and I have direct access to the back of the engine. I imagine it would be sort of a headache on a F150.
I really hope this helps somebody!
Last edited by EVERY DETAIL; 11-19-2011 at 07:08 PM.
Reason: Added part number
Hi, im just wondering the location of coolant temp sensor that sends signal to computer. Im bout to pull my hair out!! The parts store said there is 3?? Is that correct?? I found the block sensor located under manifold toward front. I found the second one in front , left of alt. On corner of manifold but was told that one only controls gauge. Wheres the 3rd for signal to computer if thats correct??? Help please