V6 GLS, Having intermittent indicated (gauge) overheating issues. No codes. Temperature gauge climbs towards red, doesn't stay there. I have OBD real-time reader hooked up- temp reading has once gone to 210 degrees but only briefly- usually to 208 degrees then back down. At idle yesterday (not hot outside) temp varied between 207 degrees and 199 degrees (the left radiator fan cycled on at 208, off at 199 degrees). Thermostat had been replaced and coolant system seems OK. I believe the sensor has been replaced as well. No leaks; water pump replaced with timing belt. If there's a high indicated temp (gauge) if I shut engine off, then start immediately, the same gauge shows "normal" at startup. (Seems if there was a *real* high temp, that gauge would return to the same high reading when I restart the engine...?) When gauge is "misbehaving", its reading doesn't seem to correspond to OBD temp readings. I'm trying to determine if there's a real overheating issue or if the gauge/sensor is faulty. Any help would be appreciated!

SOURCE: Hyundai Elantra Antifreeze Leak

if the fan NEVER comes on anymore, then that's why your engine is getting hot. You need to figure out if the fan switch relay is bad, or if the motor on the fan is bad, or something in the electrical system with the fan is not working. if the temp. sensor wasn't working, then your guage wouldn't work. I would never have used any type of stop leak in an engine cause it can clog up your return ports from your engine's cooling system and then you have real problems later with your engine. There is so much to have to check with this vehicle to see what's the problem. However, you can check to see if the fan motor works, by unplugging the fan electrical plug, and using a direct wire from your battery to give it electricity to it directly, if it comes on, then the motor isn't the problem, it's something else like a relay or something. you can also use a test light to check the plug for the fan coming from the engine to see if it's getting any electricity to it with the key turn on, just plug in the test light to each wire in the harness coming from the engine, and making sure you have a good ground connection your tester by clipping the tester to the neg battery cable, then touch each wire to see if either of them light up the tester. if they don't, then you are NOT getting fire(electricity) to the fan through the wiring which could indicate a fan relay gone bad, broken wire someplace or burned wire someplace. Takes alot to track down electrical stuff, takes time, alot of knowledge and patience. i would take your car to the dealer, unless you know a really good shop that does this kinda work. You need to be informed of this though....YOUR HEAD ON YOUR ENGINE IS MADE OF ALUMINUM AND IT DOESN'T TAKE MUCH OVERHEAT TO WARP IT AND CAUSE MORE DAMAGE THAN YOU CAN AFFORD TO PAY OUT ON . SO DON'T KEEP DRIVING THE CAR UNTIL IT HAPPENS. GET IT TO A SHOP AND MAKE SURE THEY TEST THE HEAD FOR LEAKING WATER AND LET THEM KNOW IT'S RUN IN THE RED BEFORE.... THAT'S A NO NO FOR ALUMINUM HEADS... WILL WARP THEM IN A HEARTBEAT. GOOD LUCK.

SOURCE: Sonata high temperature

Could be a bad sensor. I've seen this caused by a loose connection and may not be overheating in fact. Certainly should be checked out.

SOURCE: 2000 Elantra Overheating

First when vehicle is cold like in the morning check and make sure that the vehicle has enough coolant/ antifreeze in radiator and reservoir. If coolant is need use a 50/50 mixture of water and antifreeze. You will need some time to do this let car run at idle until the temp guage is in the middle NOT+ normal operating temperature. At this point if the thermostat should be in the open position. Let vehicle run and check to make sure that radiator fan comes on. This should come on when guage is about midway/half way. If temperature rises above half going to h/hot and fan doesn't come on, you either have a BAD FAN BAD FAN SWITCH BAD FAN RELAY OR BLOWN FAN SWITCH FUSE. You will need to check all of the following I will help if its needed. If fan comes on and doesn't go off and vehicle continues to get hot even with fan running. Feel radiator hoses and see if the lower radiator hose is cool/cold. If it is you have thermostat that stuck closed. Replace thermostat and fix problem. If all the above is good and vehicle continues to over heat. THE BAD NEW IS THAT YOU MAY HAVE A BLOWN HEAD GASKET /CRACKED HEAD /BROKEN WATER JACKET. Basically you will need a HEAD JOB at least a head gasket. ONe tell tail sign of this is oil looking like milkshake/chocolate milk-a creamish while residue in oil or antifreeze. Contact if you need hel0p. Good Luck and thanks for using FIX YA

SOURCE: location of the coolant temperature sensor

You will find this sensor where the fat hos comes from the radiator and conects to the engine block. It would be on the housing where the thermostat is located. If it is not there you should look for a sensor that has a wire connected to it anywhere on the engine block where a water inlet is located. I hope this helps. Don't forget to rate my answer, thanks.

PAUL MC G

• 1280 Answers
• Posted on Sep 12, 2009

SOURCE: fluctuating engine temp a/c sends out cold air intermittently

Here's the thing. The ECU will shut down AC if the engine temperature is too hot. If the coolant temperature sensor is malfunctioning (lying to the ECU) telling it that the temperature is hotter than it actually is, the computer will turn the AC OFF.