DTC P0137: SECONDARY HO2S (SENSOR 2) CIRCUIT LOW VOLTAGE
Fig. 63: DTC Troubleshooting Flow Chart (P0137)
Courtesy of AMERICAN HONDA MOTOR CO., INC.
NOTE:
Before you troubleshoot, record all freeze data and any on-board snapshot, and
review the general troubleshooting information See HOW TO TROUBLESHOOT
THE FUEL AND EMISSIONS SYSTEMS or HOW TO TROUBLESHOOT THE A/T
SYSTEM .
Confirmed
DTC
Pending
DTC
Freeze
Frame
DTC Description
P0137 SECONDARY HO2S (SENSOR 2) CIRCUIT LOW
VOLTAGE
1. Problem verification:
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1. Turn the ignition switch to ON (II).
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2. Clear the DTC with the HDS See HOW TO TROUBLESHOOT THE A/T SYSTEM or
HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS .
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3. Start the engine. Hold the engine speed at 3, 000 rpm without load (in P or N) until the radiator
fan comes on.
4. Monitor the OBD STATUS for DTC P0137 in the DTCs MENU with the HDS.
DTC Description
OBD STATUS
P0137 SECONDARY HO2S (SENSOR 2) CIRCUIT LOW VOLTAGE
Does the HDS indicate FAILED?
YES : The failure is duplicated. Go to step 2.
NO : If the HDS indicates PASSED, intermittent failure, the system is OK at this time. Check for poor
connections or loose terminals at secondary HO2S (Sensor 2) and the PCM. If the HDS indicates
EXECUTING, keep idling until a result comes on. If the HDS indicates OUT OF CONDITION, go to
step 3 and recheck.
2. Determine possible failure area (secondary HO2S (Sensor 2), others):
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1. Turn the ignition switch to LOCK (0).
2. Disconnect the following connector.
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Secondary HO2S (Sensor 2) 4P connector
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3. Connect terminals A and B with a jumper wire.
Terminal A Secondary HO2S (Sensor 2) 4P connector No. 1 (YEL)
Terminal B Secondary HO2S (Sensor 2) 4P connector No. 2 (BRN)
Fig. 64: Identifying Secondary HO2S (Sensor 2) 4P Connector Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.
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4. Turn the ignition switch to ON (II).
5. Check the parameter(s) below with the HDS.
Threshold
Values
Current conditions
Unit Values Unit
Signal
HO2S S2 Less than 0.12 V
Do the current condition(s) match the threshold?
YES : Go to step 3.
NO : REPLACE SECONDARY HO2S (SENSOR 2) , then do the repair verification .
3. Determine possible failure area (short in SO2 line, short in SO2SG line):
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1. Turn the ignition switch to LOCK (0).
2. Remove the jumper wire from the secondary HO2S (Sensor 2) 4P connector.
3. Turn the ignition switch to ON (II).
4. Check the parameter(s) below with the HDS.
Threshold Current conditions
Signal
Values Unit Values
Unit
HO2S S2 about 5.0 V
Do the current condition(s) match the threshold?
YES : Go to step 4.
NO : Go to step 5.
4. Shorted wire check (SO2SG/SO2 SG line):
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1. Turn the ignition switch to LOCK (0).
2. Jump the SCS line with the HDS.
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3. Disconnect the following connector.
PCM connector C (49P)
4. Check for continuity between test points 1 and 2.
Test condition IG LOCK (0)
PCM connector C (49P): disconnected
Secondary HO2S (Sensor 2) 4P connector: disconnected
Test circuit SO2SG
Test point 1 PCM connector C (49P) No. 47 (GRY)
Test point 2 Body ground
Fig. 65: Checking Continuity Between PCM Connector C (49P) No. 47 (GRY) And Body
Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES : Repair a short in the SO2SG/SO2 SG wire between the PCM (C47) and secondary HO2S (Sensor
2), then do the repair verification .
NO : The SO2SG/SO2 SG wire is OK. Update the PCM See PCM REMOVAL AND
INSTALLATION or PCM UPDATE if it does not have the latest software, or substitute a known-
good PCM See PCM REMOVAL AND INSTALLATION or PCM UPDATE , then do the repair
verification .
5. Shorted wire check (SO2 line):
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1. Turn the ignition switch to LOCK (0).
2. Jump the SCS line with the HDS.
3. Disconnect the following connector.
PCM connector B (49P)
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4. Check for continuity between test points 1 and 2.
Test condition IG LOCK (0)
Secondary HO2S (Sensor 2) 4P connector: disconnected
PCM connector B (49P): disconnected
Test circuit SO2
Test point 1 PCM connector B (49P) No. 46 (WHT)
Test point 2 Body ground
Fig. 66: Checking Continuity Between PCM Connector B (49P) No. 46 (WHT) And Body
Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES : Repair a short in the SO2 wire between the PCM (B46) and secondary HO2S (Sensor 2), then do
the repair verification .
NO : The SO2 wire is OK. Update the PCM See PCM REMOVAL AND INSTALLATION or PCM
UPDATE if it does not have the latest software, or substitute a known-good PCM See PCM
REMOVAL AND INSTALLATION or PCM UPDATE , then do the repair verification .
REPAIR VERIFICATION (OBD STATUS CHECK)
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1. Reconnect all connectors.
2. Turn the ignition switch to ON (II).
3. Reset the PCM with the HDS See HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS
SYSTEMS or HOW TO TROUBLESHOOT THE A/T SYSTEM .
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4. DO THE PCM IDLE LEARN PROCEDURE .
5. Start the engine. Hold the engine speed at 3, 000 rpm without load (in P or N) until the radiator fan
comes on, then let it idle.
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6. Monitor the OBD STATUS for DTC P0137 in the DTCs MENU with the HDS.
DTC Description
OBD STATUS
P0137 SECONDARY HO2S (SENSOR 2) CIRCUIT LOW VOLTAGE
Does the HDS indicate PASSED, FAILED, EXECUTING, or OUT OF CONDITION?
PASSED : Troubleshooting is complete. If the PCM was substituted, replace the original PCM See PCM
REMOVAL AND INSTALLATION or PCM UPDATE . If any other Pending or Confirmed DTCs are
indicated, go to the indicated DTC's troubleshooting.
FAILED : Go to step 1 and recheck. If the PCM was updated, substitute a known-good PCM See PCM
UPDATE or PCM REMOVAL AND INSTALLATION , then check the OBD STATUS again.
EXECUTING : Keep the test condition until a result comes on.
OUT OF CONDITION : Meet the test condition, and check the OBD STATUS again.
DTC P0138: SECONDARY HO2S (SENSOR 2) CIRCUIT HIGH VOLTAGE
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