P0121
0 owner reports and 23 manufacturer filings across 17 model years from Buick, Cadillac, Chevrolet, GMC.
Where P0121 shows up
Source: NHTSA manufacturer communications and complaints| Model year | Filed under | Bulletins | Owner reports |
|---|---|---|---|
| 2017 Cadillac CTS | Engine | 3 | — |
| 2016 Cadillac CTS | Electrical System | 3 | — |
| 2016 Chevrolet Express | Electrical System | 2 | — |
| 2016 GMC Savana | Electrical System | 2 | — |
| 2026 Buick Encore | Unknown Or Other | 1 | — |
| 2018 Cadillac CTS | Engine And Engine Cooling | 1 | — |
| 2018 Chevrolet Corvette | Engine And Engine Cooling | 1 | — |
| 2017 Chevrolet Express | Engine And Engine Cooling | 1 | — |
| 2017 Chevrolet Silverado 2500HD | Engine And Engine Cooling | 1 | — |
| 2018 Chevrolet Silverado 3500HD | Engine And Engine Cooling | 1 | — |
| 2017 Chevrolet Silverado 3500HD | Engine And Engine Cooling | 1 | — |
| 2016 Chevrolet Silverado 3500HD | Engine And Engine Cooling | 1 | — |
| 2026 Chevrolet Trailblazer | Unknown Or Other | 1 | — |
| 2017 GMC Savana | Engine And Engine Cooling | 1 | — |
| 2017 GMC Sierra 2500HD | Engine And Engine Cooling | 1 | — |
| 2017 GMC Sierra 3500HD | Engine And Engine Cooling | 1 | — |
| 2016 GMC Sierra 3500HD | Engine And Engine Cooling | 1 | — |
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.
What it gets filed under
Manufacturer filings that name it
Source: NHTSA manufacturer communicationsService bulletins and campaigns whose filed summary names P0121. Quoting the document number at a service desk is often the fastest route to a diagnosis someone has already written down.
- PIP61122026-05-04 · Unknown Or Other
- This Preliminary information communicates to the technician the diagnostic direction necessary to address MIL illumination with DTCs P0121, P0299, P1101 or P00C7.
- PIP4578B2017-12-18 · 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- This PI was superseded to update model years and add information concerning idle surge, reduced engine power mode, and/or DTCs P0068, P0121, P1516, P2101, P2119, and/or P2176 that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.
- PIP5424A2016-10-05 · Equipment — Other — Owners/Service/Other Manual
- This Preliminary Information communication provides information to the technician about vehicles that the engine may shut off after wide open throttle maneuvers also the Service Engine Soon Malfunction Indicator Lamp on. Technician may find Diagnostic Trouble Codes P0121, P2101 and P2119 set. Dealer should inspect the air-filter to make sure it is correct. Technician should replace the air filter
- PIP54242016-09-23 · Engine
- THIS PRELIMINARY INFORMATION COMMUNICATION PROVIDES INFORMATION TO THE TECHNICIAN ABOUT VEHICLES THAT THE ENGINE MAY SHUT OFF AFTER WIDE OPEN THROTTLE MANEUVERS ALSO THE SERVICE ENGINE SOON MALFUNCTION INDICATOR LAMP ON. TECHNICIAN MAY FIND DIAGNOSTIC TROUBLE CODES P0121, P2101 AND P2119 SET. DEALER SHOULD COMMUNICATE TO THE CUSTOMER NOT TO DRIVE THE VEHICLE AGGRESSIVELY ON TRACK LIKE CONDITIONS.
- PI15382015-10-01 · 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.
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. 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 P0121
Source: NHTSA files and the OBD-II standardCan I keep driving with P0121 stored?
Nobody can answer that from the code alone, and a site that does is guessing. A steady light generally means the fault was logged and the vehicle is in a reduced-risk mode; a flashing light means stop soon, because a misfiring engine can destroy a catalytic converter in minutes. 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.