2019 Chevrolet Blazer

I keep getting this message that pops up, "Steering Assist reduced Drive with Care". At the same time this happens the temp gauge stays on cold, the ac quits working, the engine fan is on high, and most of the time I get code PO128. We have had it in to the dealer and they said the its the thermostat or the temp sensor. From what I am reading it could be a factory issue with the EMI issue from sensitive ECT circuitry. This has been an ongoing issue for us for over a year.

At startup, I would receive a message that said, steering assist reduced. There were no check engine lights or warning lights. My air conditioning stopped working, and my temperature gauge on the dash remained at cold. I also noticed the radiator fans were on full blast, continuously. I called the dealer, and they weren't sure what was causing that. I told them I was getting codes #U0401 & P0128. They asked me to clear the codes to see if they returned. I cleared the codes, but they returned immediately on restart of the engine. I'm going to replace the thermostat but i didn't understand the #U0401 code, so did further research. I found 2017 Bulletin #17-NA-158 which seamed relevent to my issues, and Vehicle Fitment that confirmed my 2019 Chevy Blazer is included. I then came to find that the un-shielded low voltage wires for the coolant temperature sensor are routed through the same harness as high voltage coil wiring. Some of us know that EMI will affect low voltage signals. As an HVAC system designer, I know that un-shielded low voltage communication wiring cannot run parallel two line voltage power wiring. The effects are not continuous, but definitely reoccurring. I also understand there has not been a recall for this issue which surprises me. I can replace the thermostat even in its difficult position, but I don't feel comfortable in separating the low voltage wiring from the harness. I understand that dealers who are aware of this issue, charge a hefty fee to do so. It's definitely one that I can't afford.

"shift to park" message appears when parked (even if safety brake is engaged) and attempting to turn off the vehicle. The vehicle does not turn off and remains running for various periods of time. Unable to turn the vehicle off, leaving it unsecure and drains the battery. This happens consistently. I contacted my local dealership and they confirmed getting several of these reports through their shop, but no recall has been made.

The Blazer is having a recurring P0128 code. We have informed the dealership. This has been going on for 2 years or so. I reset the code with a code reader and it stays off for a few months usually. Tried to have the dealership look at it one of the last times it happened but they wouldn't just look at it...they wanted to set up an appointment. We needed the car so I reset the code again. Now it is time to get it fixed. I know it needs a thermostat and temperature sensor. The cost to install it will be close to $1000. This should not be at my cost. This is a know issue with the 3.6L engine and it affects the emissions of the vehicle along with many other parts of the engine. I am reaching out to see what can be done.