Very little Heat and CEL

[gnonne]

Been having issues with the thermostat code recently on our 2012 1.8L sedan. Was running pretty well, then I noticed very little heat and the CEL came back on while driving today. I ordered a new T-stat housing (6yrs old, 75k, doubt its covered by GM.) Radiator hose seems rather cool after driving 20 miles on highway in 10-15 F weather. Seems like t-stat is stuck open, but haven't read the code yet...

Oddly, its NOT leaking any coolant... I'm thinking of just replacing the aluminum part and not the entire housing with all the hoses and connections.
It is cold in the garage and I'd rather be out there as little as possible, but if I can't get the old t-stat off the plastic housing, I'll do the whole thing.

Thoughts?

 

[Papasonic]

I changed the thermostat assembly in our 2012 - 1.8 LTZ sedan when it had the same symptoms. Check engine light on, limited heater output temperature, AC compressor won't engage and no remote start. I purchased from an online vendor; the new one was an original GM part, but was machined from aluminum alloy; the one I replaced was made of a composite/plastic material that appeared very cheaply made and marginal in design and function. I believe the one I purchased was around $60.00 shipped.

 

[gnonne]

Connections

Is it difficult to remove the oil cooler line and the throttle body line without damaging them? How do you release the throttle body line?

 

[Papasonic]

Is it difficult to remove the oil cooler line and the throttle body line without damaging them? How do you release the throttle body line?

It's been a year since I replaced mine; I remember draining the coolant, removing the radiator hose, disconnecting the electrical connector and removing 4 fasteners. I have a link to a service manual that describes the process.
This is for the 1.8, but the manual covers both the 1.4, and 1.8.
Chevrolet Sonic Repair Manual: Engine Coolant Thermostat Replacement (LUW) - Thermostat - Engine Cooling - Engine - Powertrain

 

[Smartdave]

The oil cooler coolant line is very inaccessible without removing the exhaust manifold. However you should be fine by just replacing the thermostat part. I have done it a couple of times at this point as I have 160k on the clock


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[Palmaris]

I found my car gave me considerably more heat when I put the coolant level at least a 1/2 inch ABOVE the max fill line on the coolant reservoir. The car takes only half the time it did to reach the operating temp. YMMV but its a free fix attempt.