What does the Engine Only Traction Systems (ETS) primarily monitor during acceleration?

The Engine Only Traction Systems (ETS) primarily monitors the wheel speeds to verify if any of the wheels are spinning excessively during acceleration. This monitoring is crucial for maintaining optimal traction and preventing wheel slip, which can occur in slippery conditions or under hard acceleration. By assessing the speed of each wheel, the system can detect differences that indicate loss of traction and can adjust engine power delivery accordingly to help maintain control of the vehicle. This capability is vital for enhancing safety and stability while driving, especially on wet or icy roads.

The other choices involve various engine diagnostics, but they do not relate directly to how traction systems operate during acceleration. Monitoring wheel speeds is specific to traction management, while the other options focus on general engine maintenance or leaks, which are not directly linked to traction control.