Poor-sha

I've started having an problem where after my car has been running for about 10 minutes I get a CHECK COOLANT LEVEL message in the DIC that doesn't go away. If I shut the car off and restart it is gone and it only seems to happen on the first start of the day.

The coolant level is fine and I've tried searching the forum. Some have said that the C6 doesn't have a coolant level sensor and uses some algorithm. Othere have said there is a sensor in the reservoir but I don't see any wires going to it.

This did start after I have to unbolt and move the reservoir for a bit to replace the upper shock bushings but everything is back where it was now.

Thoughts?

bowtiguy

I've had the same issue with my tracked JSB 08 C6Z...

There are NO wires or sensor going to the tank in a C6Z. How the car knows the coolant level I still have not figured out. I took some fluid out of the resevoir when the fluid was cool to get it just at or slightly below Rec: fluid level line and it took care of it.

you might want to give that a try....

Poor-sha

Wierd. It looks like something is goofy with my coolant temp sensor and that would cause the problem since the coolant level is calculated using that as one of the inputs (thanks to Jason for clarifying that).

I just tried this experiement:

1) turn car ignition on but don't start it.
2) Set coolant temp to display in the DIC. It read ambient temp ~80F
3) Start car - coolant temp immediately drops to low 50's F
4) As car runs it slowly creeps up to 59-60F
5) Then suddenly it jumps to 161F and the CHECK COOLANT LEVEL message pops. I'm pretty sure my car has 160F thermostat so it seems like the thermostat opening causes the sensor to correct.
6) After that the coolant temp seems to track correctly and no more errors.

Any ideas? Is it possible there is an air bubble or something?

bowtiguy

bubbles should work themselves out through the high tube that attach's to the radiator shroud. thats the high point in the system both from the radiator and the heads.

Unless you just replaced the radiator and forgot to suck out the air from the top of the raditor before start-up, small amounts of air should work their way out.

1) I tried to replace the coolant temp sensor with no results.

2) I tracked back the coolant sensor wiring with no problems.

3) I replaced the T-stat because it was sticking and these codes started right as my Ron Davis Radiator started to leak.

Once I replaced both ( Radiator under warranty,, Thanks Ron D!) I still got the code. I pulled some fluid out and everything has been fine since.

songman3

According to the manual, the car does not have a coolant level sensor.

The control system uses an algorithm - an precisely defined series of data steps - to determine whether or not the coolant level in the system is low.

The ECM gathers engine RPM and Coolant Temp data and sends it to the HVAC control unit via the BCM.

The HVAC unit analyses the engine RPM and Coolant Temp data it receives with relation to time.
It uses the conclusions of that analyis to decide whether the variations in coolant temp it is seeing, with relation to engine RPM and time, are a consequence of the coolant level in the system being too low.

The surge tank has a working capacity of 0.8 liters and seemingly the system can lose up to 2 litres of coolant before the DIC message is triggered, so the surge tank can be completely empty and the 'Low Coolant' message may not be activated.

I don't know the conditions set by the algorithm, but it could be that the sharp and sudden rise in coolant temp you describe, might be the culprit with regard to triggering the DIC alarm.

Sticky thermostat - faulty coolant temp sensor - corrupt data in the HVAC unit?

LMBTom

This used to happen to me often in the winter, but hasn't been happening since the temps have gotten above 70. I also flushed my coolant sometime between winter and now. I haven't seen the message since, though It may just be related to the ambient temperature.

Anyhow, I've just ignored it (and hit the reset button) since it's obviously stupid because my coolant levels have always been fine

walhan_qtr

I had the same thing in my 07 Z06. after 5min of starting the car the massage will pop up. I checked the coolant level but it was ok. tried filling it a bit more, but still didnt fix it. so I just ignored it. I used to get it almost every day that I got used to it. but then one day, it went and I never saw it again. I didnt touch anything or do anything, it just went away by it self. (before that I had the battery disconnected for about a month) but I still saw the massage the first few days I started the car after hooking the battery back on. glad its not there anymore! it was annoying.

Poor-sha

I must admit that I wouldn't believe this if I hadn't seen it myself but that worked! I sucked ~ 3/4 liter of coolant out of the reservoir so that it is well below the full line and no more problems. The temp reads correctly and no check coolant level code. Bizarre.

flashback

same thing happened to my 2007. and it started to happen after a dealer in glendale replaced the hvac modl. for a problem with the air cond. it seems they did not reprogram the modl. corectly and screwed it up.there is a chevy s.b.for the z06 only, it is in the programing of hvac modl. another dealer had to replace the modl. and reprogram the wright way now everything is fine.

bowtiguy

It worked for me, I figured I toss it out there and see if it worked for you. Cheaper than replacing temp sensor etc... Glad it worked for you. now you can follow your oil temps on the track w/o the message display interupting you with coolant issues.

scottcolbath

I'm dusting off this thread.

The first time I saw the coolant low message, I topped off my tank. The car then proceeded to push out the excess coolant when it was running warm and the coolant expanded past the capacity of the tank. Then, after this happened a couple times, the message would appear again. The level looked OK when cold. And when warm, the level in the tank was just about to the top.

I just hit the reset button now and ignore it. Whatever the algorithm is to decide the coolant is low, it is apparently a bit wonky.

S.C.

548chevelle

i replaced the coolant reservoir a couple years ago with a smaller aluminum tank. Sorta like what the C1 vettes had. I did this to eliminate the hoses crossing over between the rad and the engine. Tank is mounted on the passenger side When cold coolant is at 1/4 level and when hot goes up to 3/4. Never had a problem.