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P0128 Code - Coolant Temperature Sensor Location?

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Location
Belleville
#1
I've had a CEL intermittanlty when its cold for "Coolant Temperature Below Regulating Temperature" Generally comes on when its 0 degrees Celsius and under, turns off after a few hundred km's at warmer temperatures. I had the recall for the coolant level sensor done, so I also have the thermostat that opens at a slightly lower temperature, and still no change. I am thinking its a glitch with the coolant temp sensor, even though the gauge shows normal operation, I've also never overheated the car. I have no problem getting heat to come out of the vents, and my coolant level is normal and fine. I haven't been able to locate the temp sensor (searching online). Does anyone have info on a part number or location for this?

Or otherwise, any info on this CEL code? Anyone encounter this?
 


OP
E
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3
Location
Belleville
Thread Starter #3
Ahh thank you, thats perfect. Does look like a bit of a pain in the ass to reach though. I'll have a look under the hood when things warm up a bit here.
 


Nowuries

New Member
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Ostfildern-Kemnat
#4
Everyone--Koozy is wrong!! Do not go through the hassle of removing the alternator, thermostat, etc. The sensor he noted is actually the oil pressure sensor. The ECT (electronic coolant temp) sensor is actually MUCH easier to get to and replace. It is underneath the big air filter outlet hose that goes up around the back/top of the engine--just remove the hose, move a couple other hoses on the driver side of the engine Fiesta ECT1.jpg , and viola! See the attached pictures!
--BTW, I was getting an error P0128 so I replaced the thermostat (which was just replaced due to the coolant system recall) and the ECT sensor. Come to find out the A-hole at Ford installed a broken thermostat (likely didn't move out the AC compressor a bit to fit properly) but I continued to find and replace the ECT sensor. The part Koozy noted is the oil temp sensor--part 3M51-9278AB. It is threaded, which made me know it wasn't right.
--TOP TIP FOR THERMOSTAT REPLACEMENT: In order to make it easy to get the thermostat housing in/out, you need to loosen the AC compressor bolts about 1/2 inch and move the AC compressor away from block and then the thermostat housing won't catch on this weird part right below it. Also, I did not have to remove the oil filter to get to the lower bolts on the thermostat housing, but if you have big hands... lord, grant you patience and mercy. Holy jeez, they were buggers.
--ECT Coolant Temperature Sensor location: In the pics, it is the bright bronze sensor in the center circled in red in Pic1. I moved the vacuum tube and some other tubes out of the way to make it easy. It has a clip, so be careful not to lose that when you loosen it to release the sensor. NOTE: Some coolant may come out if you have not drained your system so 1) don't do this when the engine is hot and 2) be ready with new sensor to "plug" it ASAP. Since I had lost most coolant due to thermostat change, it was super easy (thankfully).
 


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Nowuries

New Member
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Ostfildern-Kemnat
#6
Actually, I trusted that Koozy was right and figured I would replace the thermostat too since I had to get all the way to it anyway to replace the sensor he thought was the ECT sensor. In the end, I got lucky since I found that the thermostat was busted (thanks Ford technician....) so it ended up a good result, but had I found the right (and much easier) location for the coolant sensor earlier, I could have swapped it to test if it was the sensor that was causing the P0128 error or not.
 


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