Can anyone tell me the location of the second cooling sonsor? I know about the 1 at therm. stat housing,it's unplugged at the moment but temp gauge & coolsnt fan still works.DODGE STRATUS 2.4

no engine size stated, so there will be no Exact answers ever...
for that one fact..... (most posters fail here)
ok engine temp gauge, so....
ambient temperature is what,
are you at high altitude, ? or cold outside? just a clue here...
it's 100F here, so...
where the parts Jeep parts or aftermarket, ?
the thermostat, is it 180F, or higher, its stamped on this part.
wed need to know that, for sure.

ok, you got the wrong parts.
the dash guages is only a toy , we use a real pyro gun to read temps. at the STAT housing !!!
is the fan for RAD kicking.
not using real tools and real temp guages, means you are just guessing...
consider this.
old stat was bad, (most old ones are, they are short lived)
say it reads too low all the time, so you learn and expect its bad habits,
then put in the correct stat, (not stated what)
and now it works correctly
or
you had the 180F stat then put in the 200f and it runs hotter.
did you know the stat temp is regulated by the EPA here
are you here, ?USA? or not.
they make this car in Europe too, so..... (laws there are diffr)

or
Stat put in upside down.
or not with bleed hole (jigglepin) not up hill.
or have air on top of loop, causing the stat to go nuts and the ECT to go nuts (buy the wrong ECT,?) no name or pn. stated. so...

my guess is that if the gauge does drop , with heater on max
then the cooling system does have issues.
is it full of 50% AF?
take of cap of rad, dead cold
is it full
and at the next hot to cold cycle? is it?

The Coolant Sensor should be locates near or on the Thermostat Housing.

The 6VE1 engines coolant temp sensor is in the cross over housing on right hand front section of head just under throttle body (ECU). From memory the 6VD1 (older) engine is in similar position. There are 2 sensors one for engine ECU & one for Temp gauge the single wire one is for temp gauge which is in same cross over housing but left side.

It could well be a faulty thermostat- test or replace same.
Could also be a blocked radiator core, - check coolant or airflow is not restricted,
Ensure any radiator leaks are repaired,
Ensure coolant level is correct, without airlocks - bleed as necessary on re-fill,
Check operation of cooling fan - ensure fan runs at appropriate engine temperature - if not check sensor switch and associated relay operation.
Thermostat is located at the end of top radiator hose where it connects to engine housing.

THE SENSOR FOR THE GAUGE IS ON THE HOUSING THE UPPER RADIATOR HOSE ATTACHES TO.

Check to make sure your thermostat works right by monitoring the warming up of your engine. With a completely cold engine, start and run the engine for a few minutes, then put your hand on the top radiator hose to monitor if and when it gets warm as the thermostat opens more and more and note the gauge reading( if it works) the top radiator hose should be unbearably hot within 5-8 minutes. If the therm. opens right it should close right aswell, staying open a little while eventhough the radiator may have cooled may be what you are experiencing causing the rapid cooling and is nothing to worry about. The Hose should not get warm very soon after starting the engine. Regarding you gauge, lets take one step at a time, verify proper op. or the therm.

I'm going to assume that you have a 4.0 L6 (inline 6) engine) since that's the most common one. If not, most of instructions are the same. 1. With engine cool, or, pressure out of system, radiator cap off, remove both hoses from thermostat housing (top radiator hose connects directly to housing on front of engine). 2. carefully scrape all gasket material from housing and block. Make note of how the thermostat was installed (end with spring goes into the engine block). Since installation is vertical, I usually use silicone glue on gasket, installing thermostat into housing first, then applying gasket to housing, so that it will hold the stat in place when installing to block. (let glue dry for a while). 3. Put a thin film of silicone on engine side of gasket, position assembly on block and put in the easiest to access bolt, finger tight. Be careful not to move assembly around too much or you may cause the thermostat to go out of position. Put in the second bolt, again, finger tight. When both bolts are installed, tighten each, going back and forth, taking up tension equally (don't tighten one, then the other one all at once). 4. replace both hoses, fill to replace any coolant lost (usually not very much). Start engine and run with cap off radiator and heater full "on". Watch temp gauge.When up to operating temp, add more coolant if necessary. (also monitor radiator during this stage for overflow or overheating. it is sometimes necessary to intermittently add some coolant while engine is coming up to temp. as some overflow is normal). 5. close cap and run for several more minutes. Check hoses and therm gasket for seepage. Some re-tightening may be necessary, but if excessive you may have made a mistake you should not have to "crank down" really hard on any hose clamp or fastener. PS, I usually remove and replace spring type hose clamps with screw type. They are more reliable and easier to work with!
Good luck!

the sender for the gauge is on the cylinder head near the spark plug if you unplug it the gauge should stay all the way cold then ground it out it will go all the way hot if that reads like that replace the coolant sensor

The water temp sensor is located near the thermostat housing. This sensor is what tells the ECM to turn the fan on/off. The water temp sending unit is located near the same area. You know you have the correct sensor is because the water temp sensor has a 2 prong plug. The water temp sending unit only has 1 prong.

Finding the thermostat is easy. Just follow the top radiator hose back to the engine.
The question I have is how to get to the bottom screw of the thermostat housing.

Any Sugustions anyone?