Data Mismatch (receive data does not match what was expected)
Your vehicle's computer received data from a module that doesn't match what it expected to get, like ordering a burger and receiving pizza instead. This communication mismatch between modules prevents proper system operation.
The ECU expects specific data packets from body control modules, gateway modules, or other networked ECUs within defined timing and format parameters. When received data doesn't match the CAN/LIN protocol structure, checksums, or expected values, a mismatch fault is logged.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Data Packet Checksum | Calculated value matches transmitted value | Checksum validation failure or corrupted data received |
| Message Frequency/Timing | Data arrives at expected intervals (e.g., every 100ms) | Message delayed, missing, or arrives out of sequence |
Code B2139 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.
Once the fault is repaired, B2139 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.