TP-6903 5/16a Electrical System and Sensor Troubleshooting 69
4.7. Heated Exhaust Gas Oxygen
(HEGO) Sensor
Troubleshooting
Figure 4-14 HEGO Sensor
WARNING
Hot parts can cause severe burns.
Do not touch engine while operating or just after
stopping.
Never operate engine with heat shields or guards
removed.
Servicing the exhaust system. Hot parts can cause
severe injury or death.
Do not touch hot engine parts. The engine and exhaust
system components become extremely hot during
operation.
WARNING
Risk of Fire. Can cause severe injury or death.
Do not smoke or permit flames or sparks near fuels or the
fuel system.
Troubleshooting and/or repairing the sensors or the
ECM. A backfire due to an open fuel shut-off valve can
cause severe injury or death. If power is supplied to the
shut-off valve during ECM or sensor troubleshooting, fuel
may enter the air intake manifold or the air cleaner and
cause a backfire. Make sure that the fuel supply is turned
OFF and that the fuel shut-off valves are
DISCONNECTED from the power source BEFORE
turning the ECM power on.
Figure 4-15 HEGO Sensor Wiring Diagram
Refer to Figure 4-15 and follow the steps in the
troubleshooting chart to verify that:
The HEGO sensor is working correctly and is
not damaged.
The sensor leads have continuity (no open
circuits).
The sensor leads are not shorted.
Important: Silicone sprays or inappropriate RTV
(room temperature vulcanization) sealers can
contaminate the HEGO sensor. Contaminated HEGO
sensors can produce false or high readings resulting in
poor fuel mixtures and severe performance problems.
Always verify that the sealer is safe to use with the
HEGO sensor before using.
P27-82, O2 heater
HEGO sensor
Power from
the controller
P26
65
Sensor
owe
1
2
70J
82
70K
3
4
51
18
ECM
P26-51, Ground
P26-18, O2 signal
51A
51B
To CT sensor
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