I think you have ruled out all the possibilities except for the temp sensor.

 

Is the fan stuck on? It should not turn on until the temp gets up to about 219F OR the AC/defrost is on.

 

Yes, the fan is always on but my AC is also always on... it’s HOT in Puerto Rico! What can I do about this issue?

 

Is there no seperate code for this? Temperatures are reading accurately but it’s not heating up enough.

 

Try it without the AC for a while.

 

With a defective thermostat, the temp will be slow to rise, but should still get above 180 but will just take longer to get there.

If like you say it only gets to 160 most of the time, I'd say it points to the sensor. And no, there is not a specific code for the sensor.

 

Sorry Whopper, wrong.
P0116 ECT sensor performance
P0117 ECT circuit low voltage
P0118 ECT circuit high voltage
P0119 ECT circuit intermittent
P0128 Engine Coolant Temperature below thermostat regulating temp (180F)

Some of these will inhibit the test for the others. All except P0116 turns the AC off and fan on.

You might try replacing the sensor. At least look at the connector for corrosion.
You might try the battery lobotomy trick; disconnect the negative terminal of the battery for 10-20 minutes to reboot the computers.

 

Ahhh thanks don - I wasn't about to go looking thru the codes, but glad you found them. I can't remember anyone getting those ones before, so did a quick search - but did not spot anyone replacing a sensor.

Yeah, I'd just replace the sensor - they probably aren't that pricey.

 

I’ve changed the thermostat 2x (a Duralast then an AC Delco), put in new DexCool 50/50 coolant each time, burped several times (on an incline and level ground)... and still my temp only goes to 160 and my gauges turn off giving me the P0128 code. Tomorrow I will replace the sensor. If that doesn’t do the trick... well... I’ll let y’all know.

I appreciate everyone’s time and input on this!! Stay tuned.

 

Will be good to this one resolved. Dang fancy-complicated-computer-controlled cars eh?