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Heater quit working

2847 Views 18 Replies 4 Participants Last post by  TheStig
My wife took the car to work today, and called me about 10 minutes into the drive, and the heater hadn't started working yet. Vehicle temperature was good, but it wasn't blowing hot air. While I was on the phone with her, it started working. When she got to work and parked, "code 4" came up. Any ideas as to what this is?
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Was curious as to what these codes are that can pop up in the DIC, not in the owners manual, and if in the shop manual, may have to start at page one and go through all three manuals.

Only two instances of Code 4 on this board, one dealer claims the coolant temperature is defective, but know seems to know exactly what this code 4 is, is there also a code, 1,2,3, or 5?

See your temperature gauge is reading high, plus the check engine light is on, helpful that you posted a photo. With a scanned, should know exactly what the problem is. Least they list CEL codes.

In regards to common problems, the water pump may have developed a leak and will only get worse, recovery tank coolant level will be low. Could also even be some hose or the thermostat that is the problem. But one thing for sure, its a problem. Ha, even the coolant temperature sensor.

All of the climate controls fed into the BCM, if this shuts down the MVAC controls, good question, manual doesn't even explain this, all it does explain is how to change parts. And the way these parts prices are going, may be cheaper to replace the entire vehicle.

Knowing the CEL light would help, but with coolant problems, could crack that aluminum head in these engines, so best to call your dealer and have it trucked over.

Chevy did warranty the water pump for 150,00 miles or 10 years, whichever comes first.

Dex-cool is the only coolant to use.
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TheStig has a Canadian Cruze. The errors are numeric instead of text. As far as I can tell it's so GM doesn't have to generate both English and French language versions of the text along with the associated support for changing languages.
Learned something, so one would require a Canadian shop manual? Does that code move to the left for digits higher than 9?

Hey Stig, check your coolant levels first.
Ha, I am going to wear out my hood release the number of time I open it to check fluids. So we have a plastic recovery tank, with a plastic cap with an O-Ring around it. My peanut butter jar has a much better cap than this. And my peanut butter jar does not have 20 psi of pressure behind this cap.

Constantly tightening this cap, why does it keep getting loose? And why put that O'Ring on the very coarse threads on this cap? Couldn't have picked a worse spot, it binds when you screw it in. Adding some silicone grease does help. If they had any brains, would have used a neoprene gasket under the cap for a far superior grip. But brains are becoming history.

And should have used finer threads. When they did have brains, the recovery tank just took the overflow when using a properly designed radiator cap that took years to develop. No pressure in that reservoir plastic tank as it was called. And since its just taking the overflow, the coolant nearly isn't as hot.

So beside having cooling system leaks, this cap is the problem, Has to have a very good seal, Coolant is a 50-50 mix of water and Dex-cool, engine operating temperature is above 212*F where the water can boil off. Not anything new, called distilling that dates back over 4,000 years.

So you are wondering why we are having problems? These are the reasons. Always a reason. Watch your coolant levels like a hawk.

What else is missing is a low level coolant sensor to at least give you a warning.
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