P0037
2GR-FSE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0037: Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2)
DTC P0037 - Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2)
DTC P0038 - Oxygen Sensor Heater Control Circuit High (Bank 1 Sensor 2)
DTC P0057 - Oxygen Sensor Heater Control Circuit Low (Bank 2 Sensor 2)
DTC P0058 - Oxygen Sensor Heater Control Circuit High (Bank 2 Sensor 2)
DTC P0141 - Oxygen Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
DTC P0161 - Oxygen Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)
DESCRIPTION
In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a TWC (Three-Way Catalytic Converter) is used. For the most efficient use of the TWC, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric air fuel ratio. For the purpose of helping the ECM to deliver accurate air fuel ratio control, the Heated Oxygen (HO2) sensor is used.
The HO2 sensor is located behind the TWC, and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low).
When the air fuel ratio becomes lean, the oxygen concentration in the exhaust gas is great. The HO2 sensor informs the ECM that the post-TWC air fuel ratio is lean (low voltage, i.e. less than 0.45 V).
Conversely, when the air fuel ratio is richer than the stoichiometric air fuel ratio, the oxygen concentration in the exhaust gas becomes small. The HO2 sensor informs the ECM that the post-TWC air fuel ratio is rich (high voltage, i.e. more than 0.45 V). The HO2 sensor has the property of changing its output voltage drastically when the air fuel ratio is close to the stoichiometric ratio.
The ECM uses the supplementary information from the HO2 sensor to determine whether the air fuel ratio after the TWC is rich or lean, and adjusts the fuel injection time duration accordingly. Thus, if the HO2 sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air fuel ratio control.
MONITOR DESCRIPTION
The sensing portion of the Heated Oxygen (HO2) sensor has a zirconia element which is used to detect the oxygen concentration in the exhaust gas. If the zirconia element is at the appropriate temperature, and the difference between the oxygen concentrations surrounding the inside and outside surfaces of the sensor is large, the zirconia element generates voltage signals. In order to increase the oxygen concentration detecting capacity of the zirconia element, the ECM supplements the heat from the exhaust with heat from a heating element inside the sensor.
Heated oxygen sensor heater range check (P0037,P0038, P0057 and P0058):
- The ECM monitors the current applied to the O2 sensor heater to check the heater for malfunctions. If the current is below the threshold value, the ECM will determine that there is an open circuit in the heater. If the current is above the threshold value, the ECM will determine that there is a short circuit in the heater.
Example:
The ECM sets DTC P0038 or P0058 when the current in the HO2 sensor heater is more than 2 A. Conversely, when the heater current is less than 0.3 A, DTC P0037 or P0057 is set.
Heated oxygen sensor heater performance (P0141 and P0161):
- After the accumulated heater on time exceeds 100 seconds, the ECM calculates the heater resistance using the battery voltage and the current applied to the heater. If the resistance is above the threshold value, the ECM will determine that there is a malfunction in the HO2S heater and set DTC P0141 and P0161.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
All:
P0037 and P0057:
P0038 and P0058 (Case 1):
P0038 and P0058 (Case 2):
P0141 and P0161:
TYPICAL MALFUNCTION THRESHOLDS
P0037 and P0057:
P0038 and P0058:
P0141 and P0161 (Heater performance monitor check):
COMPONENT OPERATING RANGE
MONITOR RESULT
- Refer to CHECKING MONITOR STATUS Mode 6 Data.
WIRING DIAGRAM
CONFIRMATION DRIVING PATTERN
HINT:
- This confirmation driving pattern is used in the "PERFORM CONFIRMATION DRIVING PATTERN" procedure of the following diagnostic troubleshooting procedure.
- Performing this confirmation driving pattern will activate the heated oxygen sensor monitor (The catalyst monitor is performed simultaneously). This is very useful for verifying the completion of a repair.
1 Connect the Techstream to the DLC3.
2 Turn the engine switch on (IG).
3 Warm-up the engine until the engine coolant temperature reaches 75°C (167°F) or more [A].
4 Drive the vehicle at between 40 mph and 75 mph (60 km/h and 120 km/h) for at least 10 minutes [B].
5 Drive the vehicle 40 mph (60 km/h) or more and decelerate the vehicle for 5 seconds or more. Perform this 3 times [C].
6 Turn the Techstream on.
7 Select the following menu items: Powertrain / Engine / Utility / All Readiness.
8 Input DTCs: P0136, P0137, P0138, P0139, P0156, P0157, P0158 and P0159.
Check that DTC MONITOR is NORMAL. If DTC MONITOR is INCOMPLETE, perform the drive pattern increasing the vehicle speed and using the second gear to decelerate the vehicle.
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction Freeze Frame Data.
PROCEDURE
1. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)
(a) Disconnect the K34*1 or K57*2, V35*3 heated oxygen (HO2) sensor connector.
HINT:
- *1: Bank 1 Sensor 2
- *2: Bank 2 Sensor 2 (2WD)
- *3: Bank 2 Sensor 2 (4WD)
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance (Bank 1 sensor 2):
Standard resistance (Bank 2 sensor 2):
(c) Reconnect the HO2 sensor connector.
NG -- REPLACE HEATED OXYGEN SENSOR
OK -- Continue to next step.
2. CHECK TERMINAL VOLTAGE (+B OF HO2 SENSOR)
(a) Disconnect the K34*1 or K57*2, V35*3 HO2 sensor connector.
HINT:
*1: Bank 1 sensor 2
HINT:
*2: Bank 2 sensor 2 (2WD)
HINT:
*3: Bank 2 sensor 2 (4WD)
(b) Turn the engine switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage (Bank 1 sensor 1):
Standard voltage (Bank 2 sensor 1):
(d) Reconnect the HO2 sensor connector.
NG -- INSPECT EFI NO. 2 FUSE
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)
(a) Check the harness and connector between the ECM and HO2 sensor.
(1) Disconnect the K34*1 or K57*2, V35*3 HO2 sensor connector.
HINT:
*1: Bank 1 sensor 2
HINT:
*2: Bank 2 sensor 2 (2WD)
HINT:
*3: Bank 2 sensor 2 (4WD)
(2) Disconnect the A7 ECM connector.
(3) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):
Standard resistance (Check for short):
(4) Reconnect the HO2 sensor connector.
(5) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM
4. INSPECT EFI NO. 2 FUSE
(a) Remove the EFI No. 2 fuse from the No. 2 engine room relay block.
(b) Measure the resistance of the EFI No. 2 fuse.
Standard resistance:
Below 1 Ohms
(c) Reinstall the EFI No. 2 fuse.
NG -- CHECK FOR SHORT IN ALL HARNESSES AND CONNECTORS CONNECTED TO FUSE AND REPLACE FUSE
OK -- Continue to next step.
5. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - EFI NO. 2 FUSE)
(a) Check the harness and connector between the HO2 sensor and EFI No. 2 fuse.
(1) Disconnect the K34*1 or K57*2, V35*3 HO2 sensor connector.
HINT:
*1: Bank 1 sensor 2
HINT:
*2: Bank 2 sensor 2 (2WD)
HINT:
*3: Bank 2 sensor 2 (4WD)
(2) Remove the EFI No. 2 fuse from the No. 2 engine room relay block.
(3) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):
Standard resistance (Check for short):
(4) Reconnect the HO2 sensor connector.
(5) Reinstall the EFI No. 2 fuse.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
6. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - EFI NO. 2 FUSE)
(a) Remove the EFI No. 2 fuse from the No. 2 engine room relay block.
(b) Remove the integration relay from the No. 2 engine room junction block.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):
Standard resistance (Check for short):
(d) Reinstall the EFI No. 2 fuse.
(e) Reinstall the integration relay.
NG -- REPLACE ENGINE ROOM NO. 2 RELAY BLOCK, JUNCTION BLOCK
OK -- CHECK ECM POWER SOURCE CIRCUIT