U0121 on the 2007 Chevrolet Avalanche
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.
Nobody has written a description of this code yet.
| 08-07-30-021H | 2017-08-15. Service bulletin. This technical bulletin provides repair information to correct customer concerns of loss of high speed GMLAN communications, intermittent no crank, IP gauge fluctuation, intermittent door lock cycling /chime operation, various IP warning lamps illuminated, transmission may not shift, communication DTCs U0073, U0100, U0101, U0102, U0109, U0121 or U0140 set. |
|---|---|
| 08-07-30-021G | 2012-04-28. Service bulletin. GM: LOSS OF HIGH SPEED GMLAN COMMUNICATIONS, INTERMITTENT NO CRANK, IP GAGE FLUCTUATION, INTERMITTENT DOOR LOOK CYCLING, INTERMITTENT CHIME OPERATION, VARIOUS IP WARNING LAMPS ILLUMINATED, TRANSMISSION MAY NOT SHIFT, COMMUNICATION DTCS U0073, U0100, U0101, U0102 U0121 OR U0140 SET (REPAIR TERMINALS IN TRANSMISSION HARNESS CONNECTOR, REPAIR OPEN OR SHORTED GM HIGH SPEED LAN CIRCUITS, OPEN OR SHORTED DATA LINK RESISTOR, CORROSION OR POOR CONNECTIONS IN VARIOUS CONTROL MODULE CONNECTORS). *JS |
| PIT-4056 | 2007-09-20. Service bulletin. GMC: UNABLE TO COMMUNICATE WITH THE EBCM DTC U0121. *NJ VEHICLES EQUIPPED WITH JL4. UPDATED 9/30/08. *PE UPDATED 6/27/11. *PE UPDATED 4/6/12. *PE |
| 060845010 | 2007-01-26. Service bulletin. IGNITION SWITCH DIAGNOSTIC TIPS - DTC CODES C0561, P1629, P1682, U0101, U0121, U0155 AND/OR NO CRANK/NO START, HVAC, RADIO, ON STAR, POWER ADJUSTABLE PEDALS, AND OTHER ELECTRICAL COMPONENTS INOPERATIVE. *KB |
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.