Code Definition

B1009 — Eeprom checksum error

System: Body  |  Type: Manufacturer-Specific  |  Make: GM

About B1009

B1009 is a manufacturer-specific body diagnostic trouble code recorded for GM vehicles. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

B1009 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The Body Control Module (BCM) in GM vehicles stores critical configuration and adaptive data in Electrically Erasable Programmable Read-Only Memory (EEPROM), and maintains an inverse copy of certain memory blocks as a data integrity safeguard. DTC B1009 is set when the BCM's microprocessor performs a checksum validation by reading a stored value and adding it to its stored inverse copy — if they do not sum to zero, the data has been corrupted and this code is flagged. This type of corruption typically results from voltage spikes during jump-starting, unstable battery voltage during write ope...

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