05 Sport Track 2 sensor Thermostat Housing | Ford Explorer Forums - Serious Explorations

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05 Sport Track 2 sensor Thermostat Housing


New Member
February 3, 2014
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Year, Model & Trim Level
2005 Sport Trac
I recently had to replace the thermostat housing in my 05 sport trac due to the lower housing seam busting. The lower housing was the 2 sensor version but there was only one sensor connected to the wiring harness. I understand that this is fairly common. I didn't read enough before the repair to know to replace it with the single sensor housing so I just replace with the 2 sensor housing. The old sensors were too loose in the new housing so I replaced those as well. My question is, what is the difference between the two sensors? What would happen if I connected the wiring harness to the wrong one?

I just had a P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature) engine code pop up. I also have noticed that it seems like the temp gauge in the instrument cluster doesn't get quite as high as it used to. I'm wondering if I connected to the wrong temp sensor and it is sending the wrong temp?

I stupidly didn't replace the thermostat when I was at it, so it is possible the thermostat is stuck open.

Anyone know the difference between the sensors and if this could possibly be the problem? Or should I just go ahead and replace the thermostat?

Thanks in advance for your help.

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Grey is an Engine Coolant Temperature (ECT) sensor, and red/orange is a Temperature Gauge Sender. IIRC. my '05 ST had TWO grey ECT sensors, one to plug the unused port. I don't believe they are interchangeable on vehicles that use both because the connector plugs are keyed differently. Did you use the Motorcraft RH144 lower housing and the DY1004 ECT sensor(s) or aftermarket parts? I've read of fitment and compatibility issues with anything but OEM replacements. Start by replacing the thermostat with the stock temp Motorcraft RT1167 since it's due for relacement anyway. If not, replace the ECT sensor if it's aftermarket. BTW, although upper clearance is confined, the sensor can be replaced without removing other parts. Be careful with the tiny retainer clip and tie a string, floss, or fishing line to prevent loss. Keep posted and GL.

I went to the dealer for the parts so they are OEM. I don't recall the part numbers off hand (the receipt is at home). I do know that they gave me two sensors (different part numbers) and they looked physically different (the sensor side looked different) but the connector fit both.

I think I might try swapping the connector to the other sensor to see if that changes anything. Unless anyone thinks that might be a bad idea.

I have the same issue, I replaced the housings and found out the 2 sensors (only one is connected) are identical (light gray color) and they don't fit in the new housing because too loose.

what should I do next? buy 2 new sensors or replace o ring with bigger ones?

I went through this last summer with my '03 ST. The new one piece housing I bought had bigger sensor ports so I used thicker O-rings, dielectric grease on them and crushed the clips down more so I really had to force them into position. Haven't had a leak yet (knock on wood). I bought a variety case of O-rings from Harbor freight but you can get them at any parts store or hardware store.

If I decide to do an electric fan I'm going to keep my 2port so I can get a temp controller to screw in and then control a mark VIII fan and use an open relay spot under the hood for power