Deciphering a P0128

Hello all, I'm new to HP Tuners and trying to learn. I have a buddy who teaches me and I'm grateful for that, but I feel like I am bugging him so much! Now, time to bug someone eelse, if you'll have me.

I am reading a P0128 coolant temp below expected range.

This is a 2017 Chevy Silverado. The symptoms are the cooling fan is coming on at random times, staying on longer than normal, and the gauge is reading high.

I just did a VCM Scan. I noticed the ECT engine coolant temp on HPT is just above 125, and the gauge on the truck is about 175. I am trying to figure out if there is more that I can read, are there different sensors for the ECM and the gauge cluster, where do I go now?

I uploaded the log I took if that helps.

Thanks!

If the thermostat is good (and stock rating), and everything in the cooling system is stock and working as it should be, set P0116 & P0128 to No Error Reported. They are a right royal pain in the ass. The scanner data will also lie to you when either of those codes is active, you'd have to look at generic OBD data to see the actual coolant temp.

If anything about the cooling system is changed from stock, then also disable the codes because it's a prediction thing and there isn't any way to adjust parameters for what will trigger the codes, just turn them off.

Quote:

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Originally Posted by blindsquirrel

If the thermostat is good (and stock rating), and everything in the cooling system is stock and working as it should be, set P0116 & P0128 to No Error Reported. They are a right royal pain in the ass. The scanner data will also lie to you when either of those codes is active, you'd have to look at generic OBD data to see the actual coolant temp.

If anything about the cooling system is changed from stock, then also disable the codes because it's a prediction thing and there isn't any way to adjust parameters for what will trigger the codes, just turn them off.

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I do appreciate your input @blindsquirrel! Thanks!

Thermostat failures and coolant temp sensor failures are super common K2XX trucks just a FYI. The stock thermostat is 207 degrees, if your coolant temps once up to temp or atleast 10min of run time isn't above 180-190 degrees, I'd be replacement both parts together.