P0128 on GMC vehicles The engine is not reaching its normal operating temperature in the expected time — usually the thermostat
P0128 is named on 8 GMC model years (2017–2023): 6 manufacturer filings and 21 owner reports in NHTSA’s files, across Acadia, Sierra 2500HD, Sierra 3500HD.
Which GMC model years name P0128
Source: NHTSA manufacturer communications and complaints| Model year | Filed under | Bulletins | Owner reports |
|---|---|---|---|
| 2019 GMC Acadia | Engine | — | 7 |
| 2020 GMC Acadia | Electrical System | — | 6 |
| 2018 GMC Acadia | Steering | 1 | 4 |
| 2021 GMC Acadia | Engine | 2 | 1 |
| 2017 GMC Acadia | Engine | — | 3 |
| 2023 GMC Acadia | Steering | 1 | — |
| 2017 GMC Sierra 2500HD | Power Train | 1 | — |
| 2017 GMC Sierra 3500HD | Equipment Adaptive/Mobility | 1 | — |
A model year is listed because the code is named in its own record — a bulletin filed against it, or an owner’s complaint about it — not because every one of these vehicles sets it. Counts are documents in NHTSA’s files, not failure rates.
What GMC owners said
Source: NHTSA complaint databaseOwners’ own words, scrubbed of anything identifying. Unverified reports filed with NHTSA — what was said, not a finding that it was true.
[Diagnostic Findings] Vehicle diagnostics identified DTC P0128 - Engine Coolant Temperature Below Thermostat Regulating Temperature
GMC filings that name P0128
Source: NHTSA manufacturer communicationsBulletins and campaigns GMC filed with NHTSA whose summary names P0128. Quote the document number at the service desk — it is a diagnosis the maker has already written down.
- PIT5967 Service bulletin2023-01-04 · Steering
- This Preliminary information communicates that a vehicle may come to the dealer with a "Service Steering Message" and no codes set that pertain to the steering system. The technician is instructed to look for a P0128 and if it is set to diagnose that code and see if the message will clear.
- 22-NA-054 Service bulletin2022-03-14 · Engine And Engine Cooling
- This technical bulletin provides repair information to correct a customer concern of a Check Engine Lamp Illuminated in the DIC (Driver Information Center), Temperature Gauge Inaccurate, and/or Cooling Fans Continue Running after Vehicle is Turned Off, with DTC P0128 Set.
- 17-NA-171 Service bulletin2017-10-01 · Power Train — Automatic Transmission
- Hesitation, Stalling, Engine Speed Flare While Coasting, Unintended Acceleration Feel During a Parking Lot Maneuver, Reduced Surge in Low Speed Maneuvers, Stumble, Harsh Tip-In/Tip-Out, Park-Reverse-Drive Shift Concerns, Harsh Shifts, Erratic Shifts, Engine Vibration, Vibration, Buzz and/or Humming from Steering Wheel, Malfunction Indicator Lamp (MIL) Illuminated - DTC P0097, P054F, P24B1, P24C7,
What P0128 means
Source: SAE J2012 / OBD-IIThe engine is not reaching its normal operating temperature in the expected time — usually the thermostat.
A stored code names the test that failed, never the part that caused it. The record above is what GMC and its owners have filed about it; the code’s page across every make has the whole file.
Common questions
Source: NHTSA files and the OBD-II standardIs P0128 a known problem on GMC vehicles?
It is a documented one: NHTSA's files hold 6 manufacturer filings and 21 owner reports naming P0128 on 8 GMC model years (2017–2023). Whether it is a problem on one particular car is a diagnosis, not a count — but a bulletin that names the code on your model year is the place to start.
Which GMC models does P0128 appear on most?
2019 Acadia (7 documents), 2020 Acadia (6 documents), 2018 Acadia (5 documents).
Does P0128 on a GMC mean it is recalled?
No. Recalls are filed by campaign and matched by VIN; no recall is triggered by a scan tool. Check the VIN at nhtsa.gov/recalls, or open the model year's page here for the campaigns filed against it.