P121B on the 2015 Chrysler 300
The bulletins listed name this code in NHTSA's summary, or are about the same components. A bulletin or a recall listed here may apply to the model year. None of it is a diagnosis.
This code is specific to a manufacturer and is not described here. Its meaning is in the manufacturer's service information.
| 18-035-15 REVA | 2018-12-10. Service bulletin. Flash: 6.2L / 6.4L Diagnostic And System Improvements This bulletin involves reprogramming of the Powertrain Control Module (PCM) with the latest software. A small number of customers may experience one or more of the following symptoms and/or a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation the technician may find one or more of the following Diagnostic Trouble Codes (DTCs). Symptoms: ? Unable to accurately increase or decrease the cruise control set speed using the resume or set buttons while the instrument cluster is set on metric units. Instead of changing vehicle speed by 1 KPH when pressing the buttons, the vehicle speed will increase approximately 1.6 KPH. ? Slight spark knock condition during aggressive high speed driving which may prevent the vehicle from achieving maximum top speed. DTCs: ? P1217 - Active Exhaust Valve 1 Performance ? P121B - Active Exhaust Valve 2 Performance ? P2227 - Barometric Pressure Circuit Performance |
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| 18-045-16 | 2018-06-11. Service bulletin. Flash: 6.4L Diagnostic And System Improvements This bulletin involves reprogramming of the Powertrain Control Module (PCM) with the latest available software. A small number of customers may experience one or more of the following symptoms and/or a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation the technician may find one or more of the following Diagnostic Trouble Codes (DTCs): · P1217 - Active Exhaust Valve 1 Performance. · P121B - Active Exhaust Valve 2 Performance. In addition, customers may also comment on the following: · Unable to accurately increase or decrease the cruise control set speed using the resume or set buttons while the instrument cluster is set on metric units. Instead of changing vehicle speed by 1 KPH when pressing the buttons, the vehicle speed will increase approximately 1.6 KPH. · Slight spark knock condition during aggressive high speed driving which may prevent the vehicle from achieving maximum top speed. |
| 18-045-16 REV. A | 2016-11-07. Service bulletin. "FLASH: DIAGNOSTIC AND SYSTEM IMPROVEMENTS THIS BULLETIN INVOLVES REPROGRAMMING OF THE POWERTRAIN CONTROL MODULE (PCM) WITH THE LATEST AVAILABLE SOFTWARE. CUSTOMERS MAY EXPERIENCE ONE OR MORE OF THE FOLLOWING SYMPTOMS AND/OR A MALFUNCTION INDICATOR LAMP (MIL) ILLUMINATION. UPON FURTHER INVESTIGATION THE TECHNICIAN MAY FIND ONE OR MORE OF THE FOLLOWING DTCS: · **P2299 - BRAKE PEDAL POSITION/ACCELERATOR PEDAL POSITION INCOMPATIBLE. · P0456 - EVAP SYSTEM SMALL LEAK. · P2610 - PCM INTERNAL ENGINE OFF TIMER PERFORMANCE. · P2172 - HIGH AIRFLOW/VACUUM LEAK DETECTED (INSTANTANEOUS ACCUMULATION). · P0123 - THROTTLE POSITION SENSOR 1 CIRCUIT HIGH. · P0223 - THROTTLE POSITION SENSOR 2 CIRCUIT HIGH. · P0122 - THROTTLE POSITION SENSOR 1 CIRCUIT LOW. · P0222 - THROTTLE POSITION SENSOR 2 CIRCUIT LOW. · P0335 - CRANKSHAFT POSITION SENSOR CIRCUIT. · P0339 - CRANKSHAFT POSITION SENSOR INTERMITTENT.** · P1217 - ACTIVE EXHAUST VALVE 1 PERFORMANCE. · P121B - ACTIVE EXHAUST VALVE 2 PERFORMANCE. **THE FOLLOWING SOFTWARE ENHANCEMENT IS ALSO AVAILABLE: · CHANGE TO PURGE VAPOR CONTROL CALIBRATION.** IN ADDITION, CUSTOMERS MAY ALSO COMMENT ON THE FOLLOWING: · UNABLE TO ACCURATELY INCREASE OR DECREASE THE CRUISE CONTROL SET SPEED USING THE RESUME OR SET BUTTONS WHILE THE INSTRUMENT CLUSTER IS SET ON METRIC UNITS. INSTEAD OF CHANGING VEHICLE SPEED BY 1 KPH WHEN PRESSING THE BUTTONS, THE VEHICLE SPEED WILL INCREASE APPROXIMATELY 1.6 KPH. · SLIGHT SPARK KNOCK CONDITION DURING AGGRESSIVE HIGH SPEED DRIVING WHICH MAY PREVENT THE VEHICLE FROM ACHIEVING MAXIMUM TOP SPEED." |
| 18-045-16 | 2016-07-07. Service bulletin. This bulletin involves reprogramming of the Powertrain Control Module (PCM) with the latest available software. SYMPTOM/CONDITION: A small number of customers may experience one or more of the following symptoms and/or a Malfunction Indicator Lamp (MIL) illumination. Upon further investigation the technician may find one or more of the following Diagnostic Trouble Codes (DTCs): • P1217 - Active Exhaust Valve 1 Performance. • P121B - Active Exhaust Valve 2 Performance. In addition, customers may also comment on the following: • Unable to accurately increase or decrease the cruise control set speed using the resume or set buttons while the instrument cluster is set on metric units. Instead of changing vehicle speed by 1 KPH when pressing the buttons, the vehicle speed will increase approximately 1.6 KPH. • Slight spark knock condition during aggressive high speed driving which may prevent the vehicle from achieving maximum top speed. |
4 on file from NHTSA, as of 2026-10-19. See them in the bulletin list. A bulletin lists model years: read the document for which vehicles it concerns.