OBD-II · Network and communication (U)
U0300
Control module software incompatibility
What it means
A module has detected that its software, or another module's software or coding, does not match what it expects.
Symptoms
- Warning lights after a module was replaced or updated
- Features not working
- Sometimes a no-start
Likely causes, most likely first
| No. | Cause |
|---|---|
| 01 | used or new module fitted without coding or software update |
| 02 | interrupted software update (often due to low battery voltage during programming) |
| 03 | wrong part number module fitted |
| 04 | mismatched software levels between modules |
What to check, step by step
- 01Ask what work was done recently (module swap, software update, battery change)
- 02Read which module reports the fault and its part and software numbers
- 03Check the module part number is correct for the VIN
- 04Code or update the software with dealer-level tools, with a battery support charger connected