How to get to ECT sender?

[FiremanBob]

Recently, the temp gauge on my 2001 2.3 Duratec failed. It stays at cold and never moves even after engine is up to normal temp. I understand that I need to test the gauge and wire, and then the sender, in that order. I have found the sender on the coolant pipe behind the head. Above it is a large section of the wiring harness, which prevents me from getting at the sender. What do I have to do in order to get at the sender and test it?

Also, at the same time I have no heat. Could these two problems be related?

 

[Uncle Gump]

Fix the reason you have no heat first.

Is the system full? If it's low you won't have heat and could affect gauge sender also.

Could also be a thermostat issue. The engine may never properly warm up affecting heat and gauge.

Have you looked at live data for engine temp on a scan tool?

 

[pentode]

+1 ☝

I bought one of my current cars from a guy who owned it for 10 years before me. He said "the temp gauge is broken, it never worked since I had it." I checked the thermostat and it was stuck wide open. Fixed that and the temp gauge worked fine.

 

[FiremanBob]

Fix the reason you have no heat first.

Is the system full? If it's low you won't have heat and could affect gauge sender also.

Could also be a thermostat issue. The engine may never properly warm up affecting heat and gauge.

Have you looked at live data for engine temp on a scan tool?

Thanks. The thermostat and water pump are both less than a year old. Engine is warming up just fine as far as I can tell by the feel of the rad hoses and the increased volume in the coolant expansion tank. There is a slight amount of heat when I crank up the heater, but very little and much less than it has been for years.

I will run Forscan on it tomorrow.

But if everything else checks out, I will still need to access the ECT sensor behind the head.

 

[Uncle Gump]

Are the heater hoses both hot?

If not... plugged heater core or bad control valve maybe.

I'm no help with the sender or sensor on the duratech. I've seen folks complain about access back there.

 

[FiremanBob]

Just took a 15-mile test drive with Forscan hooked up. The code P0125 came up after about 10 miles. On the streaming diagnostics. the ECT temp started at 23C (much higher than ambient of 5C) and never got above 38C. The temp gauge never moved. The heater, even at full hot, gave hardly any warmth at all. idle remained high (1100-1200 rpm) throughout.

What should I do next?

 

[pjtoledo]

what does the cylinder head temp read? it's right in the middle of the valve cover, between plugs 2 & 3.

the ECT sensor is the orange one.

the 01s have a heater/sensor in the thermostat, yeah, really.
they are problematic, I would start there.

assuming the thermostat is stuck open, try completely blocking the radiator with cardboard, does the engine then heat up more?