A P0131 DTC is being discussed. Technician A says that an exhaust leak upstream of HO2S (bank 1) oxygen sensor could be the cause. Technician B says that an extremely rich air-fuel mixture could be the cause. Which technician is correct?
A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question

Quizplus · Accepted Answer

Technician A is correct because an exhaust leak upstream of HO2S (bank 1) oxygen sensor can allow excess oxygen that will not be accounted for by the oxygen sensor and can result in a false lean reading. Technician B is incorrect because an extremely rich air-fuel mixture could cause a P0172 DTC (system too rich), not P0131. P0131 is a low voltage reading from HO2S (bank 1) oxygen sensor, indicating a lean condition.

A P0131 DTC Is Being Discussed