Honda SH125 Manual page 107

FUEL SYSTEM (Programmed Fuel Injection)
DTC 21-1
( 0 2
SENSOR)
NOTE:
Before starting the troubleshooting, check the
0 2
sensor 4P connector
for
loose contacts or cor-
roded terminals, and recheck the DTC.
1.
0 2
Sensor System Inspection
Start the engine and warm it up until the cooling
fan comes on.
Check the
0 2
sensor with the HDS.
Standard: 0.1
-
0.3 V
I s the voltage within the standard value?
YES
-
Check the fuel supply system (page
5-33).
If the system is normal, GO TO STEP
4.
NO
-
GO TO STEP 2.
2.
0 2
Sensor Open Circuit Inspection
Turn the ignition switch to OFF.
Disconnect the ECM 32P connector by releasing
the lock lever, and the
0 2
sensor 4P (black) con-
nector (page 5-47).
Check each wire for continuity between the ECM
connector and
0 2
sensor connector.
Connection: Black/orange
-
Black/orange
I s
there continuity?
NO
-
Open circuit in the Blacklorange or
Greenlorange
-
Greedorange
Greenlorange wire.
YES
-
GO TO STEP 3.
3.
0 2
Sensor Short Circuit Inspection
Check for continuity between the wire harness
side 4P connector terminal and ground.
Connection: Blacklorange
-
Ground
I s there continuity?
YES
-
Short circuit in the Blacklorange wire.
NO
-
GO TO STEP 4.
Green/ ECM 32P CONNECTOR
0 2
SENSOR 4P
CON N ECTO R
5-28