First one popping with the CEL!!

Computer wants the engine to warm up to operating temp quickly and efficiently and stay there. The sooner it gets up to temp the sooner it can get its thumb on fuel calculation and tailpipe emissions. When they take too long to warm up it'll set P0128 "coolant thermostat below regulating temp". Fairly common code on lots of different vehicles. Even though the code states "thermostat" it can be thought of like a general cooling system fault.There's various things that can cause it to set

 

I think l read somewhere that the 4th Gen no longer has a Thermostat, it was replaced with some kind of electric control valve.

 

Yep a lot of manufacturers are going that direction.. to give the computer more control over operating temp

 

Unfortunately CAFE regs would say otherwise.

 

Obviously this shouldn’t happen on a new vehicle but I just watched a YouTube video where a guy had this(assuming the same) problem on his new colorado. Chevy told him to kick rocks and wanted to chg 1k. He fixed it in 20 minutes.

https://youtu.be/YhhjZPUVc7M?si=thOxxi_HwXmP5fnH

 

Isn't that the guy that has been posting videos of him breaking his truck on the trails and then trying to GM to warranty it?

 

lol I have no idea, I’ve only seen like 2-3 of his videos and they revolved around this shutter issue

 

Not all models of 4g Tacomas have them , so no , the shutter is not for warm up. The gm Twins use the shutters, there is a hack to remove them and fool the ecm.

 

Well in the case of this guys Chevy. It appears that the actuator not being in the correct position caused the CEL to come on. So I still am not believing the slow warmup story. Being that almost all manufacturers use these for the same purpose. That would be to meet EPA standards for 1-2 mpg more on the highway. It is the thermostat (real one or new electric one) that regulates the temperature of the engine on warmup. They should both be closed upon cold start up. If they are open, then the engine is still warm from its last running, or they are stuck open and have an issue creating a computer perceived CEL issue.