Can anybody help me with an erratic condition with my low coolant light? I thought when the sensor went bad it came on and stayed on, but mine comes and goes based on temp. Here's what i have going on:
My low coolant light went on so I pulled over and checked the level in the overflow bottle. Perfect on the full hot line, and temp gage was where it always is so I drove it home.
The next day after cooling off I checked the bottle and it was perfect full cold. Opened radiator cap, full to top of neck. Started engine and the light was off, but came on as soon as it warmed to operating temp. Temp and level in bottle still look perfect so I let it cool enough to remove the rad. cap and warmed it to operating temp with the cap off. Coolant level remained constant at the top of the neck and the light came back on. There did seem to be alot of flow from the TB bypass and I don't remember if this is normal.

Temp gage never exceeds the first position at 170ish, no drips or puddles ever, no coolant in oil, pressure test is good, and I'm running a Meziere EWP.
Has anybody seen this? was it the sensor going bad, or other issues?

 

Yes, very common. Clean sensor, replace sensor or unplug sensor are your choices.

4th Gen LT1 F-body Tech Articles

 

The level of the coolant in the reservoir has nothing to do with the low coolant sensor.

 

Correct, the sensor is on the radiator tank. I wasn't about to go and pop open the radiator cap when hot so an empty reservoir would have been a good red flag for me that the dash light was on for a reason.
My other concern was maybe the rad. was pushing coolant to the reservior when hot, but not pulling it back in when cold, causing a low rad.
Testing it the next day with the cap off pretty much proved the sensor isn't right.
It is because of the intermittent condition that I decided to seek a second opinion.

 

Always a good idea to check the vacuum line leading to the reservoir, wish I did that from the start of my overheating issues.