P0037
DTC P0037 HO2S HEATER CIRCUIT LOW (BANK 1 / SENSOR 2)Component Location:
GENERAL DESCRIPTION
In order to control emissions of the CO, HC and NOx components of the exhaust gas, heated oxygen sensor (HO2S), mounted on the front side and rear side of catalytic converter, detects the oxygen content in the exhaust gas. The front HO2S signal is used to control air/fuel ratio (closed loop fuel control) and the rear HO2S signal is used to monitor front HO2S and catalyst for proper operation.
The HO2S requires a minimum temperature to operate properly and provide a closed loop fuel control system. The HO2S contains the heater element to reduce its warming-up time and ensure its performance during all driving conditions. The ECM/PCM controls this heater element by duty cycle. The main relay supplies voltage to the heater and the ECM/PCM provides a ground circuit for activating the heater.
DTC DESCRIPTION
When ECM/PCM detects short to ground in the heater control circuit(B1 S2), ECM/PCM sets DTC P0037
DTC Detecting Condition:
Specification:
Schematic Diagram (A/T):
Schematic Diagram (M/T):
Signal Waveform & Data:
SIGNAL WAVEFORM & DATA
The HO2S requires a minimum temperature to provide a closed loop fuel control system. So the HO2S contains a heater element to reduce its warm-up time and ensure its performance during all driving conditions. The HO2S heater is controlled ON after engine start except for Cold condition and high speed acceleration. The ECM controls this heater element by duty cycle. The main relay supplies voltage to the heater and the ECM provides a ground circuit for activating the heater.
MONITOR SCANTOOL DATA
1. Connect scantool to DLC (Data Link Cable).
2. Warm up the engine to normal operating temperature.
3. Monitor "HO2S (B1 S2)" parameter on scantool.
4. Is the "HO2S Heater (B1/S2)" data displayed correctly?
YES - Fault is intermittent caused by poor contact in the sensor's and/or ECM/PCM's 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.
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 "Power Circuit Inspection" procedure.
POWER CIRCUIT INSPECTION
1. IG "OFF".
2. Disconnect HO2S (S2) connector.
3. IG "ON" & ENG "OFF"
4. Measure voltage between terminal 4 of HO2S (S2) harness connector and chassis ground.
Specification : B+
5. Is the measured voltage within specification?
YES - Go to "Control Circuit Inspection" procedure.
NO - Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
CONTROL CIRCUIT INSPECTION
1. IG "OFF".
2. Disconnect HO2S (S2) connector.
3. IG "ON" & ENG "OFF"
4. Measure voltage between terminal 3 of HO2S (S2) harness connector and chassis ground.
Specification : Approx. 3.5 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. Check resistance (S2).
1. IG "OFF".
2. Disconnect HO2S (S2) connector.
Specification:
3. Measure resistance between terminal 3 and 4 of HO2S (S2) (Component Side)
4. Is the measured resistance within specification?
YES
- 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.
NO
- Substitute with a known - good HO2S (S2) and check for proper operation.
- If the problem is corrected, replace HO2S (S2) 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.