2020 GMC Acadia engine problems

“Engine thermostat not functioning properly, therefore the display stayed on cold and would not show temp. It also cause the fan to run fast to cool engine. The AC would not cool and reduce power steering assist error message comes on. This is a known problem by GM and there is a recall for this issue on many of these vehicles, other GMC and Cadillac vehicles. Our vehicle should be added to the recall list!”

“Engine thermostat not functioning properly, opening too early and not allowing engine to operate at proper engine temperature. Check engine light comes on, reduce power steering assist error message comes on, engine temperature gauge reads cold when vehicle has been running for an extended period of time. This is a known problem by GM and there is a recall for this issue on many of these vehicles, other GMC and Cadillac vehicles. Our vehicle should be added to the recall list.”

“2020 GMC Acadia bucks/hesitates when I take off or slow down and speed back up. Mechanic looked at it can see engine is having random misfires. We have tried plugs, transmission fluid, looked at everything we could think of. The condition improves if I put into AWD but still exists and worsens for a period of time after it shifts back into FWD mode. My mechanic has done a lot of research and found that one possible issue was a stretched timing chain but since it is out of warranty I just couldn't afford to have them tear it down it is an enormous job to see if that was the issue. It also lines up with other known issues like the auto stop issues and possibly a fuel pump issue. I have seen many people complaining online about this particular issue but not many on here and no recalls on my vehicle regarding the known issues”

“Received a power steering reduced notice when starting the car, noticed shortly after driving the temperature gauge had not moved from its resting position. A few trips later it still had not moved and the check engine light came on. Mechanic looked at it said it may be a sensor quoted $1k to fix. A few days later it randomly started working and the light went off so I did not have it fixed. About 4 months later the same code displayed on the dash with the same issues. This time I noticed the ac would not work either it only blew out hot air. Also the fan under the hood turns on as soon as the car is started. Been about 3 days and it started working again out of nowhere.”

“[Symptom & Safety Hazard] While driving my 2020 GMC Acadia 3.6L V6, the Driver Information Center displayed the warning: "Steering Assist Reduced, Drive With Care" (SARDWC). Steering effort increased abruptly, the engine temperature gauge dropped to cold/zero, and the HVAC system lost air-conditioning function. The warning and reduction in steering assist presented a safety hazard and increased the risk of a crash. [Diagnostic Findings] Vehicle diagnostics identified DTC P0128 - Engine Coolant Temperature Below Thermostat Regulating Temperature. A GMC Certified Dealer technician diagnosed a failed engine coolant thermostat housing assembly. [Manufacturer Information] GM documentation links DTC P0128 and invalid engine coolant temperature signals to the "SARDWC" condition. GM Bulletin 17-NA-158 states the “SARDWC” condition is caused by an invalid coolant temperature signal and the steering module relies on coolant temperature information for steering-assist compensation. GM bulletin PIT5967 directs technicians to diagnose and repair DTC P0128 when the warning message is present. In Oct 2025, GM issued N252508350 for 2021 Acadia vehicles equipped with the 3.6L…”

“Thermostat and cooling sensor went out on my car. GMC issued a special coverage bulletin for 2021 Acadia since it's a widespread issue but not the 2020 (mine) which is also a widespread issue looking online. The repair is over $1000 and should be covered!”