Honda Civic '98 HVAC

Replacing Engine Coolant Temperature Sensor on 1999 Honda Civic temp sensor feeds the signal to dash display dial.

Over heating the engine is a serious concern. With the hood raised you should hear the motorized fan turn on just behind the radiator as the engine requires additional cooling.. If you look in from the rear of the radiator you should see the fan blades.

This electric powered motor operates on a thermostat and when the engine temperature rises this fan should come on. I'm assuming from your description that when driving and air is flowing through the radiator as the car travels the engine is nor overheating.

Check fan motor thermostat, check fan motor and check wiring.

Wiring Diagrams related to the Honda Civic
http://www.wiringdiagrams21.com/category/automotive/honda-automotive/civic

Motor engine cooling fan only runs as engine temperature requires additional cooling.

Most manufacturers do not supply the gauge with the correct temp. It is a computer generated guess that is displayed. If computer sees engine tempature getting warm then it will increase gauge. I had a car that someone removed the thermostat on and it would still show after three minutes it was at operating temp. But heater didn't put out heat for almost 45 minutes. A discussion with a gm engineer made me start testing others. Dodge crystler Mitsubishi gm and many others use this fake gauge. Dodge Cummins use it also for their oil pressure gauge. The only way to have accurate temp gauge is install a manual one or watch it through the scan tool.

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It sounds like the sending unit at the engine is faulty. Replace it first and if the problem still persists then check the gauge itself. If everything checks out make sure that the thermostat in the engine is not sticking causing the temp to rise rapidly and then when it opens it falls but shuts right away. I would check the sending unit first since that would cause the gauge to act weird.

the timing could be off you may have to have it checked and fixed hope this helps

Absolutley it could be the thermostat. Is the engine temp ok? Has the gauge changed position?

sounds like a bad head gasket. Check the oil and look for foam to tell if antifreeze is getting into engine block.

check you oil and your antifreese mine just did this to me and it didnt smell like cooland but i was loosing coolant throug the motor but not onto the ground and my idle did the same thing yours is doing i am willing to bet its the headgasket

6
Accord Civic CRV CRX Del Sol Odyssey Prelude
85-98 86-98 97-98 85-91 93-97 95-98 85-98 ECT Sensor (Engine Coolant Temperature)
defective circuit or unplugged / defective sensor
10
Accord Civic CRV CRX Del Sol Odyssey Prelude
85-98 86-98 97-98 85-91 93-97 95-98 85-98 IAT Sensor (Intake Air Temperature)
defective circuit or unplugged / defective sensor
16
Accord Civic CRV CRX Del Sol Odyssey Prelude
90-95 88-95 n/a 88-91 93-95 95 88-95 Fuel Injector System
defective circuit or unplugged / defective fuel injector

check your wiring for dirty connections or broken wires, you may have wires that are rubbed through or connectors that are not making full contact. you will need an ohm meter and check wires for continuity. a wiring diagram will be needed.

hi my name is brad i see you are haveing a problem and i think i might know the problem. if you have done all of that to your car and it still over heating you might have a blown head gasket one way to check is to pull your thermostat out and fill your coolant leaving the cap off then start you car let it rrun a few minutes and if you see bubbles the radiator its the head gasket even though you wont have coolant in your oil or out the tail pipe. if you check that and ther is no bubbles i have one other spot for you to check ( dont know if you have the 1.5 or 1.6 sohc ) but if you have the 1.6 sohc with the mpfi you should check on the throttle body at the idle air control valve(IAC) you will see two small line`s that have coolant some times on hondas with high millage the line will fill with crud and that can cause a problem.. if you have any other honda needs please let me know

Brad Ross