So far I've seen 3 temp sensors. A call to the dealer said there are something like 4 sensors to measure coolant temp. I know of the 3 I've seen and disconnected, none of them seem to change the temp gauge.

Here are the ones I've checked by unplugging:

-The one on the thermostat housing
-The one on the front passenger side of the head
-The one on the passenger side of the head

Is there another one somewhere?

 

It depends on the vehicle you drive? See my signature to see what info to provide.

 

OMG.. I cant believe I left that out.

1995 Accord LX 2.2 non vtec 5sp

 

Thanks, you can put that information in your signature, so you never have to remember.

Anyway, there are four sensors.

Temp switch A: On thermostat/lower radiator hose housing. Has two wires and a green plug. Will turn on both fans when coolant is above 200F when the engine is running. It is an on/off switch.

Temp switch B: On the housing where the upper radiator hose clamps to the engine. Also has green plug and two wires. Will turn on one fan when coolant is above 223F when the engine is not running. It is an on/off switch.

Engine coolant temperature sending unit. Is on the side of the cylinder head facing the passenger side of the car. It is the closest sensor to Temp switch B. It only has one wire going to it. It controls the temperature gauge in your car, so its signal (resistance) varies.

Engine coolant temperature sensor (ECT sensor): It is on the same face of the cylinder head facing passenger tire, but closer to the windshield. It has two wires going to it. This sends the coolant temperature to the engine computer, so the engine computer can balance the air/fuel mixture. It signal/resistance varies too.

 

Thank you for the detailed information. This is exactly what I needed! and I'm sure this will help many more to come. Thanks again.

 

To PAHonda: Your description of where to find the four sensors was excellent. Thank you. If the sensor going to the ECM is bad, will the car start?

 

Often (not always) it'll start because the sensor can fail in a way that the ECM thinks the engine is cold. Then as the engine warms up, it'll run worse & worse because the ECM still thinks the engine is cold.

In any case, it'll fire a bit, cough & sputter. Does yours do any of that?

 

bad ect should set a check engine light, car will go into limp mode, and as described above, probably run like crap...what is the year/engine?????????

 

guys i am new to this forum, i really need your help, my temp gauge in my car moves a little, but looks stuck, it wont move pass the c sig, what can i do, everything is ok in the car, I am unable to find the sending unit

 

On the '00 the gauge is controlled thru the ECT and PCM.

The testing is a bit involved, highly suggest a service manual. You can get a good one for ~$27 -CD Shipped or ~$22 for a download from automanualsource