A/F Sensor Troubleshooting - Honda BF135A Manual

• A/F Sensor Troubleshooting

DTC 48-5: A/F sensor current is abnormal
1. Symptom reproduction test
-1. Connect the HDS pocket tester and clear the DTC
once. If the DTC can not be cleared, go on the trou-
bleshooting.
-2. Start the engine and warm it up for 5 minutes or more
by running the engine at 3,000 min
load.
-3. Check the DTC again using the HDS pocket tester.
Does the DTC 48-5 appear?
YES – Perform "2. A/F sensor line open circuit
check".
NO – Temporary failure (Disappears)
2. A/F sensor line open circuit check
-1. Turn the ignition switch OFF. Disconnect the A/F sen-
sor connector and the ECM connector A.
-2. Check for the continuity between the No. 1
(White/Black) terminal of the A/F sensor harness side
4P connector and the No. 4 (White/Black) terminal of
the ECM connector A.
ECM CONNECTOR A
AFV1
(WHITE/BLACK)
VIEWED FROM THE
TERMINAL SIDE
Is there the continuity?
YES – Go to the step 3.
NO – Repair open in the wire between the A/F sen-
sor and the ECM.
5-49
-3. Check for the continuity between the No. 2
-1 (rpm) under no
A/F SENSOR
HARNESS SIDE
4P CONNECTOR
(Black/Yellow) terminal of the A/F sensor harness side
4P connector and the No. 14 (Black/Yellow) terminal of
the ECM connector A.
ECM CONNECTOR A
VIEWED FROM THE
TERMINAL SIDE
Is there the continuity?
YES – Replace the A/F sensor and recheck. If there
is abnormality, substitute a known-good ECM
and recheck.
NO – Repair open in the wire between the A/F sen-
sor and the ECM.
BF135A•BF150A
A/F SENSOR
HARNESS SIDE
4P CONNECTOR
AFC1
(BLACK/
YELLOW)