The Lemon IndexP129F is a manufacturer-specific code, so its exact meaning depends on the make. Full P129F page
12 owner complaints · the #5 code GMC Sierra owners name · 6% of GMC Sierra complaints that name a code (every car: 0.4%)
2019–2023 GMC Sierra · most: 2023 (4), 2020 (3), 2022 (2)
GMC Sierra owners named P129F in 12 complaints to the U.S. government (NHTSA), most often on the 2023, 2020 and 2022 model years. The part they name most is the fuel pump (5 complaints). Complaints are owner reports, not proof of a defect.
GMC Sierra model years that report P129F
Owner complaints naming P129F, 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 fuel pump, in 5 of the 12 complaints (42%). 3 of those mention it being replaced or repaired, and 1 say the problem came back afterwards.
- Fuel pump5 complaints3 mention a repair or replacement, 1 of them says the problem came back · what GMC Sierra owners paid
4 complaints mention a recall and 4 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 P129F
25% of these complaints say the check engine light came on.
- Stalls or shuts off67%8 of 12 complaints
- Loses power or goes into limp mode33%4 of 12 complaints
- Won't start or hard to start25%3 of 12 complaints
- Transmission slips or shifts hard17%2 of 12 complaints
- Warning lights and electrical faults17%2 of 12 complaints
Share of the complaints naming P129F whose text also describes each problem. A complaint can describe more than one.
Repair costs
GMC Sierra fuel pump replacement cost
Recalls on these GMC Sierra years
- Engine · 2021, 2022, 2023 · issued 2025
The connecting rod and/or crankshaft engine components may have manufacturing defects that can lead to engine damage and engine failure. NHTSA 25V274000 - Electrical · 2019, 2020 · issued 2019
The battery positive (B+) cable rings may have been manufactured with excessive glue, potentially causing an intermittent electrical connection between the B+ cable and alternator. NHTSA 19V888000 - Fuel system, gasoline · 2020 · issued 2019
The fuel pump may be missing a pressure regulator, allowing for over-pressurization of the fuel system. NHTSA 19V837000
3 recalls for the same systems (electrical, engine and fuel) on the GMC Sierra model years above. A recall for the same system isn't proof it's behind P129F. Recall work is free at any dealer: check a VIN at nhtsa.gov/recalls or with our VIN check.
Keep going
- P129F: meaning, causes and every car that reports it
- GMC Sierra reliability by year
- 2023 GMC Sierra problems and recalls
Other codes GMC Sierra owners report
P129F on other cars
Chevrolet Equinox (12) · Chevrolet Silverado (11) · GMC Terrain (10)
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 P129F means
P129F is a manufacturer-specific code: each carmaker decides what it means, so the same code can point to different problems on different brands. We haven't verified its meaning for Gmc yet. A dealer or a scanner with the maker's software can tell you exactly.
Check the complaints yourself
NHTSA complaint numbers (search them at nhtsa.gov): 11774342, 11764687, 11763825, 11753689, 11752901, 11748812, 11746738, 11728466, 11685410, 11627460, 11573939, 11486180.
Quick answers
Which GMC Sierra years have the most P129F complaints?
In complaints to NHTSA, owners of the 2023 (4), 2020 (3), 2022 (2) GMC Sierra named P129F most (12 complaints in all, 2019–2023). Raw counts, not a failure rate.
What fixes P129F on a GMC Sierra?
Owners most often name the fuel pump (5 of 12 complaints). That's what owners wrote, not a diagnosis: have a shop confirm the cause with a scan and tests before replacing parts.
Sources: NHTSA owner complaints that name P129F on the GMC Sierra, 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.