Briggs & Stratton VANGUARD 810 EFI Repair Manual page 20

16
DTC P0031/P0032 Oxygen Sensor (HO
Circuit Description
The HO sensor voltage varies from about 1.0
2
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 tem-
perature is below 600°F (360°C). An open sen-
sor 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 P0031 indicates that the sensor
has developed an open circuit and is operat-
ing in Open Loop mode. DTC P0032 indicates
circuit resistance is low and voltage being
returned to the ECM is too high.
VIOLET WHITE
A
RED
From
Main Power Relay
Signal Voltage Low or High
GREY
B
C
WHITE/GREEN
GREY/BLACK
J2 07
J2 17
Oxygen
Oxygen
Sensor
Sensor
Signal
Heater
Control
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.
Section 2: Troubleshooting DTCs
HO
2
Sensor
BLACK
Inline
D
Connector
BROWN
J2 10
5 Volt
Return
ECM
) Heater
2
Diagnostic Aids