While a low Bank 1 efficiency in the catalyst system can negatively impact the overall performance and emissions of your vehicle, it is unlikely to directly cause significant engine damage. However, it's essential to address the efficiency issue promptly to prevent potential long-term effects on the engine and other components. If the catalytic converter is not functioning optimally, it can lead to increased emissions, reduced fuel efficiency, and potential strain on other engine components. Over time, these factors could contribute to engine wear and affect its longevity. Therefore, it is advisable to have the catalyst system inspected and repaired as soon as possible to maintain the optimal operation of both the catalytic converter and the engine.