Can engine knock be from bad gas?

Yes, engine knock can result from bad gas, particularly if the fuel has a lower octane rating than required for the engine. Low-quality fuel may also contain impurities or additives that can lead to improper combustion, further contributing to knocking. Additionally, gasoline that is stale or contaminated can affect performance and lead to knocking. Regularly using fuel that meets your engine's specifications can help prevent this issue.