I have a 2012 Sonic with 35,318 miles on it. For a about a month, it's been throwing the "thermostat loose connection" code and has been idling increasingly rough. I asked about this when I bought the car, but the check engine light wasn't on at the time. They told me the rough idle was normal. It has gotten SUBSTANTIALLY worse. Multiple mechanics say they can't find anything wrong.
I don't have the time or money to continuously search for this phantom issue. It's killing my mpgs and making me increasingly nervous to drive.
If anyone has any idea of what this is or how to fix it, that information would be greatly appreciated. I've seen multiple people report similar issues with the sonic and cruz, so there must be a solution.

I'm seriously considering trading it in on an Elantra. Chevy is starting to concern me with recalls and all of the issues I've seen and heard about lately.

 

Hello Mbounds13,

I certainly understand your desire to reach a resolution for these concerns and do apologize for the inconvenience caused. If you could send us a private message, we'd be more than happy to contact the dealership on your behalf to work toward a potential resolution. Should you send an inquiry, please include your VIN, mileage, contact information, and preferred dealership. Thank you for your time and have a great evening!

Jasmine
Chevrolet Customer Care

 

Thermostat loose connection code ? Unplug the electrical connector from the thermostat . Look for damage , dirt , corrosion . Clean as necessary . Look at the connector on the thermostat . Clean as necessary . Plug things back in securely . Clear the codes & drive it . See if things change and / or the codes come back .

If they do & I am guessing it is out of warranty , replace the thermostat yourself and replenish the antifreeze you loose .

You were told the rough idle was normal ? You believed them ?

Do you know how to tell if a car salesman / saleswoman is lying to you ? If their mouth is moving .

I would like to talk to you about some ocean front property in Colorado .................

Now , you are thinking of trading cars over this ? That sounds like an even better idea than you believing them about the rough idle !

Fix it or get it fixed and drive it until you have gotten your money out of the car ( and it is paid for ) . At least until the 90,000 - 100,000 service is due .

Does your engine have a timing belt or timing chain . What mileage does the owners manual indicate replacing it ?

Our 2015 Sonic 1.8l has a belt & I think it calls for replacement at 97,500 miles . I think the 6 speed automatic transmission comes up for service around that mileage , too .

Cars require maintenance , period . Fact of life .

Now , from what I read , the Sonic has a known fault with the thermostat . Design fault / error . I think they should recall and fix them for free . But no one cares what I think .

God bless
Wyr