What would cause the temp gauge on a 2001 Nissan Altima to fluctuate from midrange to hot and back down to mid range again car is not overheating gauge just moves up and down and the fan comes on?

Answer 1

my 2001 nissa. Altima gxe just started doing this it's not the connectors my mechanic said today that it was something to do with the gauge and that it needs to be replaced. Common for this year and make and model this is actually pretty common on our altimas. locate the sensor behind the intake manifold and remove the connector. clean it and then slightly pinch the terminal together. usually its from a dirty and loose fitting connector. __________________

* * * * NEVER replace any part till you know the problem. Open the hood and with the engine at operating temp. see if the fan or fans are running. If not check the coolant temp. sensor located where the top radiator hose connects to the engine, where you put the thermostat. Turn on the a/c and the fan should start. If so you will know the fan and relay are ok. If fan is ok you probably have a radiator partly plugged. Go to a RAdIATOR shop, not an auto repair, and have them check it out. Stay away from dealers. oh yeah, and the area between the condenser and the radiator has a good chance to accumulate dirt and debris and should be checked. * drivebelt defective or out of adjustment, radiator core blocked or grille restricted, fan blades broken or cracked, cap on the coolant reservoir is not mantaining proper pressure, or needs lower degree thermostate Other causes of overheating could be a clogged radiator, either internally or bug clogged externally.

Another possibility could be a missing plastic air dam broken off underneath the radiator. These funnel air into the condenser/radiator at highway speeds and are frequently missing because of curbs or animals. found lots of technical info at http://www.altimas.net/tsb/ Look at bulletin number NTB02-047. This explains how to troubleshoot poor heater performance and it gives a procedure for replacing the thermostat. If it's an immediate change, then my guess is that the wire on the Temp gauge sensor is loose. The engine block cannot suddenly change temperatures at the range your describing. __________________

IT IS A KNOWN DEFECT! But Nissan won't pay for it. lol. all you have to do is replace the sensor. I'll give you a picture of it.

http://www.autozone.com/images/produ...2su4072003.jpg At autozone, it is part SU4072 called Coolant Temperature Sensor or the Temperature switch. WAIT UNTIL ENGINE IS COOL!!!!! then change it out. It is located on the top of your engine coming from your radiator near your alternator. it really is a 2 minute job. It will be a different socket size than what is in your car already. so don't freak out when you get it and try to put it on and it is a different mm size to tighten it up.

It VERY WELL MIGHT BE ON VERY TIGHT!! just to let you know. mine was a beep to get off.

Professionally, everyone should change this out if they havent' done so already.

EDIT!!--

okay, after looking at the picture of it and checking out my engine I think the name might be the Temperature Switch.

here is a picture of it on the top of my car. trust me, turn on your car unplug it and watch your temp thing drop to zero. once you replace it... it won't ever do it again.

I took a picture of it using my cell phone here it is.

http://a97.ac-images.myspacecdn.com/...d24eff1128.jpg The ECTS is not the one that the gauge uses; that sensor is used by the ECM. You want the Thermal Transmitter.

The bottom arrow. If you want the thread I pulled this from http://www.nissanclub.com/forums/gen...5-minutes.html Ignore the BS, you'll find some good info.

Now I removed the thermostat paying special attention to where the air bleed valve was facing on the thermostat (12 o'clock) See pic of the thermostat with the air bleed valve marked.

http://i2.Photobucket.com/albums/y10...hermostat5.jpg

http://i2.photobucket.com/albums/y10...ermostat11.jpg

I was replacing the thermostat, so you don't need to do this if you're just replacing the radiator. I put an red arrow that shows the path that the bypass hose used to take. Next, you need to clean the thermostat housing and water neck surfaces of the old Nissan silicon.

http://i2.photobucket.com/albums/y10...ermostat11.jpg

Nissan silicon is a lot like glue, so it's hard to get off. You DO NOT want to use any kind of metal scraper on the water neck, or the polished surface of the thermostat housing. You'll scratch up the surface and cause leaks. I used a plastic scraper I got a Autozone. There is no paper gasket to worry about, but the Nissan silicon is hard enough to remove. It probably took me 30 minutes to get both the water neck and thermostat housing clean enough to reassemble. I forgot to take a pic of the clean housing. I put the new thermostat in the housing with the bleed valve at 12 o'clock and put blue silicon on the water neck before reassembling. Tighten the water neck bolts down evenly, a little at a time, to 56 in-lbs. NOT ft-lbs.

http://i2.photobucket.com/albums/y10...hermostat3.jpg

I put a new bypass hose on, as well. I try to use Nissan parts, when I don't think the prices are over-inflated. All 3 hoses costed only $48.

http://i2.photobucket.com/albums/y10...hermostat4.jpg

http://i2.photobucket.com/albums/y10...ermostat10.jpg