Oxygen sensors can be used to record air/fuel ratio data.

• A. Only on intake
• B. True
• C. False
• D. Sometimes

Answer: (B)

Oxygen sensors provide a direct reading related to how much oxygen is remaining in the exhaust, which reflects whether the air/fuel mixture is lean or rich. The sensor’s signal—narrowband indicating around the stoichiometric point, or wideband giving an actual lambda value—can be logged as air/fuel ratio data. So, even though these sensors live in the exhaust, their output is used specifically to determine and record the air/fuel ratio, making the statement true.