Oxygen Sensor Module - Operation

OPERATION

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Two different six-wire Oxygen (O2) sensors are used. These sensors are titled 1/1 upstream, and 1/2 downstream. A separate O2 sensor module (1) is also used.

The engine after treatment system monitors the O2 content in the diesel engine exhaust. The Powertrain Control Module (PCM) monitors the exhaust gases for oxygen content and varies the rich/lean fuel mixture of the intake air fuel mixture to adjust the system. This diagnostic monitors the status message broadcast by the O2 Sensor Module (1) for the upstream O2 sensor's internal heater circuit. The PCM will set the fault if it receives a Failure Mode Indicator (FMI) message from the O2 Sensor Module. The PCM will illuminate the MIL lamp immediately when the diagnostic runs and fails. The PCM will turn off the MIL lamp diagnostic runs and passes in four consecutive drive cycles.