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john -aka eauto
john -aka eauto, The Car Guy
Category: Ford
Satisfied Customers: 16007
Experience:  ase tech over 15 years in the field
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99 ford expedition: 5.4L..service engine soon light..temp gauge

Resolved Question:

99 ford expedition 5.4L
service engine soon light came on
vehicle began to run poorly, temp gauge stopped working and temp light came on. gauge started working and engine ran normally
OBD II reader p1299.
please help
Submitted: 7 years ago.
Category: Ford
Expert:  john -aka eauto replied 7 years ago.

most likley a bad colant temp sensor or a wire issue to the sensor


Customer: replied 7 years ago.
Sorry but my truck doesn't have a ECT (engine coolant temperature) sensor. it only has a CHT (Cylinder Head temperature) sensor
Expert:  john -aka eauto replied 7 years ago.

same thing the cht sensor it is the cht or the pigtail going to it

Customer: replied 7 years ago.
i asked service at ford and they told me that it might be a heater coil, or bad raditor, or bad water pump. what is the likelyhood that it is actually one of those? I bought the CHT sensor today and was planning on putting it on as soon as i take the alternator loose.
Expert:  john -aka eauto replied 7 years ago.
if your temp gauge is not working its sensor or wire related not a heater CORE or radiator or water pump
Customer: replied 7 years ago.
my temp gauge works, then all of sudden it shoots staight up at the same time the temp light comes on and the car feels like it doesn't want to go. accelerator pedal can be to the floor and still not going anyfaster. service enging light comes on and code reads p1299. if i pull over and turn the car off and the turn it right back on the temp gauge is back to normal, temp light is off and the car runs fine. the service engine soon light stays lit. if i don't pull over, it seems to right itself, just takes longer to do so.
Expert:  john -aka eauto replied 7 years ago.

sounds like maybe a head gasket issue i would have a block test performed or a leak down test to confirm or deny this theory....but when temp spikes and its a power loss its generally a internal leak

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