P0121 on GMC vehicles The throttle position sensor and the engine's behaviour disagree
P0121 is named on 5 GMC model years (2016–2017): 6 manufacturer filings and 0 owner reports in NHTSA’s files, across Savana, Sierra 2500HD, Sierra 3500HD.
Which GMC model years name P0121
Source: NHTSA manufacturer communications and complaints| Model year | Filed under | Bulletins | Owner reports |
|---|---|---|---|
| 2016 GMC Savana | Electrical System | 2 | — |
| 2017 GMC Savana | Engine | 1 | — |
| 2017 GMC Sierra 2500HD | Engine | 1 | — |
| 2017 GMC Sierra 3500HD | Engine | 1 | — |
| 2016 GMC Sierra 3500HD | Engine | 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.
GMC filings that name P0121
Source: NHTSA manufacturer communicationsBulletins and campaigns GMC filed with NHTSA whose summary names P0121. Quote the document number at the service desk — it is a diagnosis the maker has already written down.
- PI1538 Service bulletin2015-10-01 · Electrical System
- This preliminary informational bulletin provides repair information on Engine Control Module (ECM) reprogramming to correct a customer concern of experiencing a slight hesitation and/or sag. Upon further inspection, DTCs P0101, P0106, P0121, P1101 may be set.
- PIP4578B Service bulletin2017-12-18 · Engine And Engine Cooling
- This PI was superseded to update model years and add information concerning idle surge, reduced engine power mode, and/or DTCs P0068, P0121, P1516, P2101, P2119, and/or P2176 that may be experienced on high mileage vehicles. Please discard PIP4578.
What P0121 means
Source: SAE J2012 / OBD-IIThe throttle position sensor and the engine's behaviour disagree.
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 P0121 a known problem on GMC vehicles?
It is a documented one: NHTSA's files hold 6 manufacturer filings and 0 owner reports naming P0121 on 5 GMC model years (2016–2017). 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 P0121 appear on most?
2016 Savana (2 documents), 2017 Savana (1 document), 2017 Sierra 2500HD (1 document).
Does P0121 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.