I'm having a weird problem with my '02 Accord. I noticed about 2 weeks ago that the temperature gauge will be where it's normally at, but then it will sometimes goes all the way down to "cold" for no apparent reason. Then it will fluctuate between "C" and normal. Sometimes it will eventually go back to normal again and stay there, but other times it will either stay at "C" or keep fluctuating for the rest of the ride.

I took my car to the dealer to check it out, but the technician said there was nothing wrong with the cooling system, so I'm stumped. The car still drives fine, but I'm concerned about any long-term problems that may result from these weird temp fluctuations.

Any ideas on what the culprit could be? Thanks in advance.

 

My bet: gauge problem and/or someting is flaky on the circuit board that drives the gauge itself. Just to be sure, I'd like to know the OBD II port is not reporting any stored codes and would pull out my infrared thermometer (good ones available on Amazon for reasonable cost) and point it to the thermostat housing to know what the temp is when the gauge reports that it's cold after the car is clearly warmed up .. especially if it's showing below normal when the A/C fans are running...

 

Thanks so much for the reply. A gauge problem would be a relief compared to the alternatives.
Whatever the problem is, I assume that the car is OK to drive? (I had assumed it's OK since the gauge never went above normal, but I wasn't 100% sure.)

Thanks again for your help, my friend!

 

You're welcome, tho' (as I also stated "just to be sure") I personally would not assume it's OK without some other verification; e.g,. when nominally warmed up, the temperature is within operating range (the Scangauge on my son's 99 Accord V6 typically flucuates in the 180-190s; I can only recall it above 200 for a very short period when it had some intake crud issues that have been resolved. Do the A/C fans cycle on and off as normal? And, I'm still fond of using one of to at least get a clue and/or having a tech (not at a dealership) show me the temps using an industrial strength OBD II reader, when the car is clearly warmed up. If it really is the gauge, eventually it should be fix; lest it under-report a real issue down the road.

 

There is something wrong with your cooling system, it has air pocket(s) in it! I had same exact scenario as you many many years ago in my still reliable Accord. As I drove the coolant temperature gauge would fluctuate between cold and normal engine temperature, I could see the needle moving! At the time I was going to school in Tulsa and Mr. Gonzales, a former ASE certified automobile technician, invited me to his house one weekend so that he could take a look. Sure enough, there was an air pocket in the cooling system that would circulate in the hoses and each time it passed thru the temp sensor it threw its readings off. The thing is that you cannot actually tell there is air in the cooling system in this cased, you just got to assume there is and do a thorough coolant system bleed.

Don't be so inclined to blame a faulty sensor ! !

Good luck and do yourself a favor, bleed the cooling system. You can do it yourself, not hard at all!

Dave

 

Thank you SO much for this message. After reading your reply, I took my car to an acquaintance who's a mechanic. I explained all of the above to him (without mentioning the possible air pockets), and he took a look at it. He called me later in the day and said that there was nothing wrong with the car, BUT there were air bubbles in the system!! So I got that taken care of, and everything's fine now.

Thanks again for your help...you nailed that one, man!