A system and method are directed towards a pseudo multi-master operation on a serial bus. The pseudo multi-master operation allows multiple devices without standard multi-master functionality to operate on the serial bus as masters. In a disclosed example, the serial bus is an Inter-Integrated Circuit (I2C) bus, which is isolated when an adapter card requires access to the I2C bus, such as to update vital product data (VPD) to a memory device, and to cache the updated VPD to a chassis management module.