Temp gauge problem
 

I am a proud owner of a beautiful 1999 Civic Si for 8 years now. I only have 61K original miles on it. Pluse im the original owner!!

I never had any major problems with it until now. For some odd reason my temp gauge in my car works but dosent haha if that makes any scents. Well let me explain. First off i live in Pennsylvania and i do NOT drive my car in the winter. Before i put it into storage in the fall of last year (2008) My temp gauge worked fine when it was warm out during the day. It would read fine like the day i bought it but when it is cold and chilly outside at night it wouldnt hardly work. Like now i just had it out and my temp gauge will only be right at the C mark or not even touching it (this is while i drive around all night and day) this last couple weeks of this month. NOTE i always let my car warm up for 5 or 10 min before i drive it. I do this with every car i owned. I had my car out these last couple weeks cause the roads here have no snow anymore and the days are some what warm plus i miss driving my car ya know but when im driving around my temp gauge will move just a hair above the C mark and other times it wont touch the C mark at all. Now if i dont drive it and keep it at idle for a long period of time my temp guage reads normal like it is summer outside but when i drive it it will go back down to the C mark. Like i said before it only does this when the weather is cold but when the weather is nice and warm my temp gauge works absolutely FINE. So if any one can help me with this problem i will be really thankfull

Thanks Ian

Re: Temp gauge problem
 

Time to replace the thermostat, sounds like it is stuck open, or not closing completely. 94

Re: Temp gauge problem
 

But my car has heat. if the thermostat was messed up wouldnt it not throw out heat

Re: Temp gauge problem
 

Yes, it will still throw heat. Your engine coolant is around 100 degrees farenheight even when it is indicating C. Normal operating temperature when the gauge is in the middle is around 170 degrees, so 100 degrees is cold for your engine, but it is nice and warm for your heater inside the car.

1. You should never run the heater in your car until it has reached normal operating temperature because you are robbing heat from the coolant that your car needs to warm up.

2. What fcm said is correct, based on what you described, it sounds exatcly like a stuck thermostat. Perhaps it was damaged by the extreme cold or something. In any case, you should go ahead and replace it. It is very simple and cheap. The thermostat itself is like $20 I think, and the job shouldn't take you any more than an hour. Be sure to pick up a gallon of coolant while you're at the parts store to top off with.

3. Once you have replaced the thermostat, make sure that you bleed the coolant system properly because Hondas can be very prissy about air in the coolant lines. It causes all sorts of wierd problems.

4. Once you get it fixed, come back here, and update your thread with your results so others can learn.

Re: Temp gauge problem
 

My garage is heated and i always let my car warm up for 10 min or so. when i pull it out of my garage i always make shure my temp gauge reads normal. Witch it does. like right now im sitting in it and the temp gauge reads fine. right were it is apost to be!! The sad thing is when i leave my garage and drive around my temp gauge will go down to the C mark.

Well my HONDA garage here told me that it is my ECT sensor. You know that sensor that go's in the side of my motor. Its only like $30 and some but before i do anything i will get a new thermostat and go from there.

I really am thankful for the help guys

Re: Temp gauge problem
 

ECT sensor only controls the temp gauge and maybe a trigger for ECU/ECM to limit RPM if engine over heats.
ECTS/RFS controls the rad fan, will turn rad fan on when engine coolant reaches 190-200 degrees fahrenheit.

If rad fan is coming on normally then the problem is the ECT sensor, if not then the problem is the thermostat, to test, block off rad with cardboard and keep an eye on the temp gauge and rad fan, if/when rad fan comes on, [temp. gauge should be reading hot] remove cardboard and temp. gauge should start dropping right away, at some point the rad fan should turn off.

If all the above is as described, replace thermostat and you should be good to go.

We do 2-3 of these a week... http://www.airwolfeautoair.com/ ;) 94

Re: Temp gauge problem
 

had tis same problem two days ago in my crx. replaced th t-stat and she now runs @ normal temps all the time. very easy fix, and gives that extra piece of mind knowing that it won't stick closed and overheat. t-stat and gasket cost me $14.99 @ napa and 1 gallon of coolant was $9.99.

Re: Temp gauge problem
 

It is most likely your thermostat, but run the diagnostic that fcm advised you to. It is simple, takes like 30 min.

Then come back and post your results.

Re: Temp gauge problem
 

?

Re: Temp gauge problem
 

I will get a new thermostat here over the weekend and also change my coolent.

i will keep ya guys posted.

Thanks again

Re: Temp gauge problem
 

Hey guys again thanks for the help!!

I did buy a new thermostat but i had to work DOUBLE shifts at work over the weekend and i had no time to put it in and again i have double shifts this week. Work has been over kill these last couple of weeks

But i will keep you guys posted

Re: Temp gauge problem
 

My car is doing the same exact thing. Its a Honda CRV. I just bought it not to long ago, its a 99 with a 164,000 on it and when when the heater is on the temperature gauge is reading cold.. When i turn off the heater the thermostat goes back to normal. Whats up with that? Anybody know what i should do