Briggs & Stratton VANGUARD M490000, Repair Manual

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DTC P0131/P0132 OXYGEN (HO2) SENSOR
Circuit Description
The HO
2
sensor voltage varies from about 1.0 volt if the
exhaust is rich down to about 0.1 volt if the exhaust is
lean.
The sensor behaves like an open circuit and produces
no voltage when the exhaust temperature is below 600°F
(360°C). An open sensor circuit or cold sensor causes an
open loop operation.
The sensor heater provides for faster sensor warm-up.
This allows the sensor to become active in a shorter
period of time and remain active during a long extended
idle.
An active DTC P0131 indicates that the sensor has
developed an open circuit and is operating in Open Loop
mode. DTC P0132 indicates circuit resistance is low and
voltage being returned to the ECM is too high.
Diagnostic Aids
Check for the following conditions:
Poor harness connection. Inspect harness connectors
for backed out terminals, improper mating, broken locks,
improperly formed or damaged terminals, and poor
terminal to wire connection.
Always clear DTCs after performing repairs.
Not for
Reproduction