The Lemon IndexThe engine isn't reaching normal temperature fast enough. Full P0128 page
34 owner complaints · the #1 code Chevrolet Blazer owners name · 58% of Chevrolet Blazer complaints that name a code (every car: 0.8%)
2019–2023 Chevrolet Blazer · most: 2020 (15), 2019 (12), 2021 (4)
Chevrolet Blazer owners named P0128 in 34 complaints to the U.S. government (NHTSA), most often on the 2020, 2019 and 2021 model years. The part they name most is the thermostat (18 complaints). Complaints are owner reports, not proof of a defect.
Chevrolet Blazer model years that report P0128
Owner complaints naming P0128, by model year. Raw counts: years that sold more get more complaints, so this is each model year's record, not a failure rate.
What owners say caused it or fixed it
The most-named part is the thermostat, in 18 of the 34 complaints (53%). 13 of those mention it being replaced or repaired, and 4 say the problem came back afterwards. Next: wiring or a connector (3).
- Thermostat18 complaints13 mention a repair or replacement, 4 of them say the problem came back · what Chevrolet Blazer owners paid
- Wiring or a connector3 complaints2 mention a repair or replacement, 1 of them says the problem came back
6 complaints mention a recall and 5 mention a warranty.
Counted from the owners' own words: a part counts when a sentence names it with a cause or repair word. What owners wrote, not a diagnosis. A shop should confirm the cause before replacing parts.
Symptoms owners describe with P0128
44% of these complaints say the check engine light came on.
- Overheats18%6 of 34 complaints
- Warning lights and electrical faults12%4 of 34 complaints
Share of the complaints naming P0128 whose text also describes each problem. A complaint can describe more than one.
Codes owners report with it
P01F0 2
Other codes named in the same Chevrolet Blazer complaints, and in how many.
Repair costs
- Thermostat replacement$1,2004 bills · middle bill
Repair bills owners named in these 34 complaints (4 in all). Owner reports, not a quote: costs vary by shop and region.
Keep going
- P0128: meaning, causes and every car that reports it
- Chevrolet Blazer reliability by year
- 2020 Chevrolet Blazer problems and recalls
P0128 on other cars
GMC Acadia (23)
The details
How we count
We read every owner complaint in the NHTSA file whose text names this trouble code, and count the ones filed about this model (matched by the make, model and model year on the complaint). Mileage is what the owner entered on the form.
Parts: a complaint counts for a part when one of the owner's own sentences names that part together with a cause word (failed, bad, diagnosed, caused by, leaking ...) or a repair word (replaced, repaired, new, reprogrammed ...). "Came back" means the same complaint also says the problem returned or the repair didn't fix it. These are counts of what owners wrote, not a diagnosis, and one complaint can name several parts.
Complaints are reports, not proof of a defect, and most owners never file one. Popular models get more complaints, so the counts are not a failure rate. The code meaning is the standard SAE J2012 definition in our own words, or the carmaker's meaning where we verified it for that make.
What P0128 means
The engine isn't reaching normal temperature fast enough. The heater may blow cool and fuel economy drops.
Drive on, get it checked. You can usually keep driving. Have the code read at your next service or within a few weeks.
- Thermostat stuck open
- Faulty coolant temp sensor
- Low coolant
Check the complaints yourself
NHTSA complaint numbers (search them at nhtsa.gov): 11773043, 11740828, 11738607, 11738523, 11738512, 11737156, 11731894, 11729613, 11723438, 11718805, 11716857, 11709700 and 22 more.
Quick answers
What does P0128 mean on a Chevrolet Blazer?
Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature). The engine isn't reaching normal temperature fast enough. The heater may blow cool and fuel economy drops.
Which Chevrolet Blazer years have the most P0128 complaints?
In complaints to NHTSA, owners of the 2020 (15), 2019 (12), 2021 (4) Chevrolet Blazer named P0128 most (34 complaints in all, 2019–2023). Raw counts, not a failure rate.
What fixes P0128 on a Chevrolet Blazer?
Owners most often name the thermostat (18 of 34 complaints), then wiring or a connector. That's what owners wrote, not a diagnosis: have a shop confirm the cause with a scan and tests before replacing parts.
Can I drive my Chevrolet Blazer with P0128?
Drive on, get it checked. You can usually keep driving. Have the code read at your next service or within a few weeks.
Sources: NHTSA owner complaints that name P0128 on the Chevrolet Blazer, counted by The Lemon Index; NHTSA recalls; repair bills owners named. Meanings: SAE J2012 in our own words. Owner reports, not a diagnosis or repair advice for your car.