P0137
DTC P0137 HO2S CIRCUIT LOW VOLTAGE (BANK 1 / SENSOR 2)Component Location:
GENERAL DESCRIPTION
HO2S (B1/S2) is in the rear side of Catalytic Converter to check the proper operation of catalyst. Oxygen density after the catalytic converter has to be within specific range (around 0.5 V when there is no acceleration and deceleration). If the oxygen density changes in accordance with HO2S (B1/S1), it means the poor performance of catalytic converter.
DTC DESCRIPTION
If the sensor output is below 0.06 V under enable conditions, ECM/PCM sets DTC P0137.(This DTC might be caused by the malfunction of Heater circuit, so, check the heater circuit first.)
DTC Detecting Condition:
Specification:
Schematic Diagram (A/T):
Schematic Diagram (M/T):
Signal Waveform & Data:
SIGNAL WAVEFORM & DATA
The rear HO2S amplitude is lower when compared to the front HO2S because the oxygen is stored/consumed during the conversion process. This is the normal signal waveform of the rear HO2S at idle.
MONITOR SCANTOOL DATA
1. Connect scantool to DLC (Data Link Cable).
2. Warm up the engine to normal operating temperature.
3. Monitor "HO2S (B1S2)" parameter on scantool.
4. Is the "HO2S (B1S2)" parameter displayed correctly?
YES - Fault is intermittent caused by poor contact in the sensor's and/or ECM/PCM1s connector or was repaired and ECM/PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO - Go to "Terminal and Connector Inspection" procedure.
NOTE: This DTC might be caused by the malfunction of Heater circuit, so, check the heater circuit first.
TERMINAL AND CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminal condition. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES - Repair as necessary and go to "Verification of vehicle Repair" procedure.
NO - Go to " Signal Circuit Inspection " procedure.
SIGNAL CIRCUIT INSPECTION
1. IG "OFF".
2. Disconnect HO2S (B1/S2) connector.
3. IG "ON" & ENG "OFF"
4. Measure voltage between terminal 2 of HO2S (B1/S2) and chassis ground.
Specification : Approx. 0.45 V
5. Is the measured voltage within specification?
YES - Go to "Component Inspection" procedure.
NO - Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
1. Visual Inspection.
1. IG "OFF"
2. Disconnect HO2S (B1/S2) connector.
3. Check that HO2S (B1S2) is contaminated or damaged by foreign materials.
4. Has a problem been found?
YES - Go to "Check ECM/PCM" as follows.
NO
- Substitute with a known - good HO2S (B1/S2) and check for proper operation.
- If the problem is corrected, replace HO2S (B1/S2) and go to "Verification of Vehicle Repair" procedure.
2. Check ECM/PCM.
1. IG "OFF" and disconnect B1S2 connector.
2. Connect scantool and Key "ON".
3. Select simulation function on scantool.
4. Simulate voltage at terminal 2 of HO2S (B1/S2) signal connector.
5. Does the signal value of HO2S (B1/S2) change according to simulation voltage?
YES - Thoroughly check connectors for looseness, poor connection, bending, corrosion,contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
NO
- Substitute with a known - good ECM/PCM and check for proper operation.
- If the problem is corrected, replace ECM/PCM and go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Clear the DTCs and Operate the vehicle within DTC Enable conditions in General information.
3. Are any DTCs present?
YES - Go to the applicable troubleshooting procedure.
NO - System is performing to specification at this time.