How can the air filter restriction indicator on the M1120 be reset?

Answer: C — Push the yellow button on bottom of gauge

The air filter restriction indicator on the M1120 can be reset by pushing the yellow button located at the bottom of the gauge. This action is designed to clear the restriction reading from the indicator, allowing for a new measurement to be taken if the air filter condition changes. Pushing the yellow button is specifically intended for this purpose, as it directly interacts with the mechanism that tracks air filter performance. This ensures that operators have an accurate depiction of filter status after maintenance or inspection work has been performed. In contrast, the other actions, such as turning the key to the ON position or engaging the red button on top of the gauge, do not serve the function of resetting the restriction indicator. Additionally, removing and reinstalling the gauge is usually unnecessary for resetting the indicator and could lead to complications or damage if not performed carefully. Therefore, understanding the specific design and functionality of the gauge is crucial for maintaining the vehicle's operational efficiency.