I have a red light that stays on that is between and below the 5k and 6k mark of the Tach. It looks like low water? Has a DOWN arrow ( used to think it was telling me to downshift and didnt turn off, lol ). I had low water and filled it to the top 2 days ago and the light is still on. The last oil change I used Valvoline high mileage for 4K miles and the oil cap had green foamy **** on it!!! I immediately thought head gasket...but my friend said its the crappy stuff in the oil (detergents?). Well now I am not sure if the green sludge was related to the light in my car. The car runs at 180 or below, and always has. Thanks---

 

The light is your low coolant warning light and yes you may have a head gasket leak. Drain the oil and see if it looks milky.

 

Also, check to see if your coolant is still full. If it is, then that crappy low coolant sensor has gone bad.

 

I hope the sensors are cheap....where are they located, and how hard are they to replace?---

 

It's directly below the fill cap about 6"

Held in with a clip from what I remember

http://shbox.com/1/low_coolant.jpg

 

Take the battery out and they a pretty easy to change. Just make sure that clip is on all the way, I've had mine come out while I was driven and as soon as I hit WOT, boom, and a lot of steam. That mistake killed my opti.

 

the thing is right smart to get to, unless you have small paws. i think it was @60 bucks at autozone. about the same at the dealer.

 

I fixed mine permanantly... buy unpluging it....

 

Exactly.

 

Alwayscode: in your original post you said that you had to add water to the radiator....have you checked it since to see if the water level dropped again? If the level is truely low, then your sensor is working fine. If the radiator is full and the low coolant light is on, then you have a faulty sensor.

 

I filled it to where it overflowed yesterday....then drove to work today. The light stayed on....and the water level stayed maxed out. Time to try the sensor, THANKS GUYS---