P0128 on GMC ACADIA
What P0128 Means on Your GMC ACADIA
Real GMC ACADIA Owner Reports (Source: NHTSA Complaints Database)
"On [XXX] my 2017 Acadia Denali started driving poorly and a steering assist reduced message appeared. I had O'Reilly scan for error messages and they were: P0128 and P0826-00. The dealership confirmed that they would need to replace the thermostat."
"Within a day of taking possession of the car, September 20, 2024, with odometer reading 76,352 , warning message in instrument cluster appears stating action required “steering assist is reduced, drive with care”. Following day, A/C stop working while driving."
"P0128 Apparently what happens when the temp sensor on the T-Stat housing goes bad it sends a signal to the ECM that the engine is overheating, causes the temp gauge to peg to "C", shuts down A/C Compressor Clutch engagement to not exacerbate the Overheat condition and super speeds the cooling fans."
"Seemingly at random a warning will pop up on the driver dashboard “Steering assist is reduced at this time”. This will lead to a engine coolant temp reading of 0 degrees, no a/c and reduced steering functionality."
"The contact owns a 2019 GMC Acadia. The contact stated that while driving at an undisclosed speed, the message "Steering Assist Fault - Drive with Caution" was displayed."
Data from NHTSA Vehicle Complaints Database. All reports are filed by vehicle owners directly with the U.S. Department of Transportation.
Common Causes of P0128 on GMC ACADIA
Percentages based on NHTSA complaint component analysis for this vehicle.
Complaint Trend by Year
What To Do Next
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1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if your vehicle is covered.
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2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50-$150) pinpoints the root cause before you spend money on parts.
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3
Compare repair quotes
Get 2-3 quotes. Dealer vs independent shop prices often differ 30-50% for the same repair.