91 f150 302 5spd,,,,hello...had check engine light come on while driving and it seems to stay on now all the time no lack of performance that i can tell..checked codes and got 21-engine coolant temperature and 24-air charge temperature.....i can understand if a sensor goes bad (21) but what else could give me that sensor hit???? truck does not overheat...and the air charge temp sensor (24)...i wasent aware this engine even had one not to mention were the heck is it...anyone have any ideas.....thanks

 

ACT is in the intake manifold on the drivers side - the connector has a yellow wire and a black wire going to it. The ECT is to the left of the thermostat housing. Did you check the codes after the truck was warmed up? If the truck was cold, those codes can come up even with good sensors.

 

hi...thanks for the info....went ahead and changed both sensors the act sensor was loaded with black goo stuff...after running engine lite came on again ...this time it showed a code 11 and a code 33 for the egr valve..funny how the warning lite only came on when the truck was moveing and not at idle reving the motor..anyway changed the egr and it seems ok so far...thanks for your help