P0128 The engine is not reaching its normal operating temperature in the expected time — usually the thermostat
85 owner reports and 228 manufacturer filings across 133 model years from Acura, Buick, Cadillac, Chevrolet and others.
Where P0128 shows up
Source: NHTSA manufacturer communications and complaintsShowing the 25 model years where P0128 appears most; it is on file for 133 in total.
A model year appears here because the code is named in its record, not because every one of these vehicles sets it. Counts are mentions in the federal files, not failure rates — nobody publishes the denominator.
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P0128 by make
The same record, one make at a time: the model years, bulletins and owner reports that name P0128 on that maker’s vehicles.
What it gets filed under
What owners said
Source: NHTSA complaint databaseOwners’ own words, one per nameplate, scrubbed of anything identifying. These are unverified reports filed with NHTSA — they are what was said, not a finding that it was true.
Companion symptoms reported: inoperative/incorrect temperature gauge, cooling fans running at high speed continuously, A/C performance loss, DTC P0128
On May 27, only five days and approximately 96 miles after purchase, a diagnostic showed Check Engine FAIL with codes P0128 and P0456
[Diagnostic Findings] Vehicle diagnostics identified DTC P0128 - Engine Coolant Temperature Below Thermostat Regulating Temperature
The vehicle was taken to the Auto Zone and connected to a diagnostic machine, and DTC: P0128, P1326, and P0014 were retrieved
Also p0128 code and no start / electrical drain, and engine light started flashing numerous occasions had to stop the vehicle
228 manufacturer filings name P0128. Start with what the maker wrote down.
A code names the test that failed, not the part. A bulletin that names it is often a diagnosis someone has already written down — quote its number at the service desk.
Manufacturer filings that name it
Source: NHTSA manufacturer communicationsService bulletins and campaigns whose filed summary names P0128.
- 09-98-22R Service bulletin2026-08-31 · Electrical System
- This bulletin announces the availability of new reprograming files for the Engine Control Module (ECM) developed to remedy the following DTCs: P0016, P0017, P0018, P0019, P0014, P0024, P0128, P2109. If any of the DTCs listed above are found to be stored in the ECM, follow the procedures outlined in the bulletin. This is an revised version of the original bulletin.
- TSB 25-2348 Service bulletin2025-07-25 · Electrical System
- Some of the vehicles listed in the Model statement above may exhibit an incorrectly illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) P0128, P0420, and/or P0430 stored in the powertrain control module (PCM). This may be due to the software in the PCM.
- 9100287 Service bulletin2024-01-18 · Equipment — Electrical
- Thermostat Assy For 2022-2024MY 3.6L Pentastar Upgrade with P0128 failure code. PRIOR TO PERFORMING ANY THERMOSTAT REPLACEMENT, PROCEED WITH INSPECTION INSTRUCTIONS FROM THE LATEST VERSION OF STAR ONLINE PUBLICATION S2309000014
- 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.
- 09-75-21 Service bulletin2021-07-28 · Engine And Engine Cooling
- This bulletin announces the availability of NEW reprogramming files to correct DTC P0128.
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. It is the starting point of a diagnosis, not its conclusion — the same code has several possible causes and the cheap one is not always right.
Common questions about P0128
Source: NHTSA files and the OBD-II standardCan I keep driving with P0128 stored?
Nobody can answer that from the code alone, and a site that does is guessing. A steady light means a fault was logged and the car should be checked soon; a flashing light means a severe misfire — slow down and get it seen as soon as possible, because severe misfire can quickly damage the catalytic converter. The safe read of this page is the mileage and the components, not permission.
Does a code mean the car is recalled?
No. Recalls are filed by campaign and matched by VIN, and none of them are triggered by a scan tool. If you want to know whether an open recall applies to one specific vehicle, check the VIN at nhtsa.gov/recalls — that is the only source that settles it.
Why do the counts here differ from other sites?
Because these are not estimates. Every number on this page is a count of documents in NHTSA's own files: manufacturer communications that name the code in their filed summary, and owner complaints that name it in the narrative. We do not model, weight or extrapolate them.
Will clearing the code fix it?
Clearing turns the light off and erases the freeze-frame data a technician would have used to work out what happened. If the condition is still there the code returns, usually within a few drive cycles, and the diagnosis now starts from less information than before.