A technician is viewing a scan tool data stream to diagnose an OBD II system. The downstream HO2S has the same voltage switching rate as the upstream HO2S. Technician A says the air/fuel ratio is too rich. Technician B says the catalytic converter may be defective. Who is correct?
A) A only
B) B only
C) both A and B
D) neither A nor B

Question

Quizplus · Accepted Answer

If the downstream HO2S (heated oxygen sensor) has the same voltage switching rate as the upstream HO2S, it indicates that the catalytic converter is not effectively storing oxygen and may be defective. Technician B is correct.

A Technician Is Viewing a Scan Tool Data Stream to Diagnose