When I'm driving coolant temp gauge hovers either below or just above cold. Idle is also a bit high at around 1100. Now when I'm just idling for a 5 minutes or so, the temp gauge starts to go up to where it should be and idles normal at about 800rpm. Other than that the motor runs fine, no leaks.

 

sounds like the thermostat could be stuck open. I would try replacing that first. Do you have heat in the car?

 

^^x2.
because you say the engine idles high while gauge reads low, i'd have to say it's probably reading accurately. the only thing that determines minimum coolant temp is the thermostat.
or the fan is staying on for whatever reason. but you'd be able to see that right away

 

heat still works fine

 

I would try changing the thermostat first, it's the cheapest. Then if the problem persists you may have a faulty sensor. But, Considering the gauge does work once it idles for an extended period I would lead to believe it's the thermostat.

 

make sure you use only oem thermostats. i still believe the problem is the coolant temp sensor. my friend's integra did the same thing and we replaced the thermostat and did not change a thing.

 

1. guy says heat works fine

2. you guys all jump to the thermostat

3. even with an open thermostat the temp gauge will move somewhat

what the real problem likely is?

side of your head there is a small sensor with one wire that sides on to it. sensor is about the side of a pencil, smallest one of the left side of the head looking right at it. that sensor is what your cluster uses

 

well, it actually uses a sender. not sensor. the sensor runs to the pcm.
and reason i figured t-stat is because he says his idle corroborates the engine temp readings on the gauge. ie, low reading on gauge, high idle. temp creeps up and idle lowers.
that's why i figure it's reading accurately

 

I would ask the OP when the heat starts working, obviously not right away, but how long after starting the engine do you get good heat

I agree, it sounds like everything is working properly other then the long heat up time, I also agree it sure sounds like a stuck open thermostat.

And it may just be semantics, but ECT switch for the rad fan, ECT sensor for the ECU/ECM and ECT sending unit for the temp. gauge. 94

 

does that sensor control the idle? or just the coolant temp gauge. I'm not questioning your knowledge. I'm new to Hondas and just trying to gather knowledge myself.

I guess it could be the sensor, but the weird part is he says while driving its cold, while idling it starts to heat up a little bit. I would think with a faulty sensor it would be on and off all the time, ya know?

they're both simple fixes, check the sensor first.

 

It was probably 30F out today. Heat warmed up after 10 min of driving which seems normal. I can basically idle my car up to normal operating temp no prob. Once I start driving for say 15 min depending on how fast I'm going the gauge will drop back to cold. Then I can idle it back up without a hitch.

 

i overlooked that for some reason

does make sense on it being a stuck open thermostat. under $20 at acura and the sender in the side of the head is like $10, replace both, see what happens

 

definitely stuck t-stat then.
when you drive, the pump moves more coolant. plus the air flow through the rad cools. the t-stat regulates minimum coolant temperature

 

^^x2 i've had the exact same problem. Changed the thermostat and problm was fixed.

 

Hi guys i´m having the same problem here in Brazil , when is stoped temperature back to normal , when is driving falls like when i started at home i already changed the thermostatic valve but still the problem , should i change the sensor? Thank you sorry for the english.

 

Sounds like thermostat is not working, even if you just replaced it, I would pull it and test it.

The only thing that would keep the engine cold is an open thermostat. 94

 

The problem with your car is the Engine Coolant Temperature Sender. I had the same problem and replaced the thermostat, thermostat sender, temp gauge, until finally I replaced this item and the problem went away. This piece is what measures the temperature of the coolant and sends the signal directly to the temp gauge. It is number 13 in this diagram and you can get one for around $10 on Amazon: