35
19 690 01 Rev. --
KohlerEngines.com
EFI SYSTEM
Removal Inspection
NOTE: Apply anti-seize compound only to threads.
Anti-seize compound will affect sensor
performance if it gets into lower shield of
sensor.
1. If sensor has heavy deposits on lower shield,
engine, oil, or fuel may be source.
2. If heavy carbon deposits are observed, incorrect
engine fuel control may be occurring.
3. If sensor is at room temperature, measure between
signal leads, black wire (Pin C) and grey wire (Pin D)
attached to sensor. If resistance is less than one
megohm, sensor has an internal short.
4. With sensor at room temperature measure heater
circuit resistance, purple wire (Pin A) and white wire
(Pin B), resistance should be 8.1-11.1
Ω
.
5. If a damaged sensor is found, identify root cause,
which may be elsewhere in application. Refer to
Troubleshooting-Oxygen Sensor (O
2
) table.
6. A special "dry to touch" anti-seize compound is
applied to all new oxygen sensors at factory. If
recommended mounting thread sizes are used, this
material provides excellent anti-seize capabilities
and no additional anti-seize is needed. If sensor is
removed from engine and reinstalled, anti-seize
compound should be reapplied. Use an oxygen
sensor safe type anti-seize compound. It should be
applied according to directions on label.
Troublshooting-Oxygen Sensor (O
2
)
Condition
Possible Cause
Conclusion
Low voltage output.
Shorted sensor or sensor circuit.
Shorted lead wire.
Wiring shorted to ground.
Replace sensor or repair wiring.
Contamination of air reference.
Remove source of external
contamination, protect air reference
area.
Air leak at sensor or gasket, sensor
upper shield damage.
Use recommended torque at
installation, replace gasket or sensor.
Revise application exhaust.
Shield sensor from damage.
High voltage output.
Silica poisoning.
Replace sensor.
Contaminated gasoline.
Use high quality fuel.
Engine problem; mis
fi
re.
Correct cause of mis
fi
re.
Excessive rich air/fuel ratio.
Check for high fuel pressure
Leaking injector
Liquid fuel in vent line
Wiring shorted to voltage.
Repair wiring.
Open circuit, no activity from sensor.
Broken element.
Sensor dropped.
Hard blow to engine or exhaust
system.
Defective sensor.
Thermal shock.
Replace sensor.
Slow time response.
Open heater circuit.
Improper handling.
Carbon deposits.
Replace sensor.
Improper fueling.
Correct fueling.
Incorrect or contaminated fuel.
Use high quality fuel.
Excessive engine oil consumption
causing exhaust contamination or
other exhaust side contamination.
Correct engine condition.
Heater circuit open/shorted or out of
speci
fi
cation.
Repair short in harness wires, replace
sensor.
