Briggs & Stratton VANGUARD M490000, Repair Manual

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DTC P0131 Signal Voltage Low (Non-Scan Diagnostics)
Step Action Yes No
1 1. Disconnect and reconnect HO
2
sensor and ECM J2 (Black)
connectors.
2. Turn Ignition ON, Engine OFF.
3. Clear codes.
4. Turn Ignition OFF, and then back ON.
5. Does DTC return?
Go to step 2. Problem corrected.
2 1. Turn Ignition OFF.
2. Back probe terminal C (Grey/Black wire) of HO
2
sensor
connector.
3. Connect terminal C back probe to red meter test lead on DVOM.
4. Back probe terminal D (Brown wire) of HO
2
sensor connector.
5. Connect terminal D back probe to black meter test lead on
DVOM.
6. Set DVOM to read volts DC.
7. Start and run engine for at least 2 minutes.
8. With engine running, observe voltage on DVOM.
9. Is reading 600 – 950 millivolts DC?
HO
2
sensor OK. Go to step 3.
3 1. Turn Ignition OFF.
2. Remove probe from terminal C, and back probe ECM connector
terminal J2-17 (Grey/Black wire).
3. Start and run engine.
4. Observe voltage on DVOM.
5. Is reading 600 – 950 millivolts DC?
HO
2
sensor OK. Verify that both
HO
2
sensor and ECM
J2 (Black) connectors
are fully mated.
NOTE: If reading is
below 300 millivolts DC,
inspect exhaust system
for cracks or leaks
between muffler and
cylinder head (gaskets).
If everything is OK,
replace HO
2
sensor.
HO
2
Sensor Connector ECM J2 (Black) Connector
Not for
Reproduction