- Open in HO2 sensor heater circuit
- HO2 sensor heater (for sensor 2)
- Integration relay (EFI MAIN)
- ECM
| Last Modified: 11-29-2007 | 1.6 C | |
| Service Category: Engine/Hybrid System | Section: Engine Control | |
| Model Year: 2008 | Model: Sequoia | Doc ID: RM000000PFA062X |
| Title: 2UZ-FE ENGINE CONTROL: SFI SYSTEM: DESCRIPTION (2008 Sequoia) | ||
|
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
Refer to DTC P0136
.
HINT:
When any of these DTCs are stored, the ECM enters fail-safe mode. The ECM turns off the Heated Oxygen (HO2) Sensor heater in fail-safe mode. Fail-safe mode continues until the ignition switch is turned off.
|
DTC No. |
DTC Detection Condition |
Trouble Area |
|---|---|---|
|
P0037 P0057 |
Heated Oxygen (HO2) sensor heater current less than 0.3 A (1 trip detection logic) |
|
|
P0038 P0058 |
Heated Oxygen (HO2) sensor heater current more than 2 A (1 trip detection logic) |
|
|
P0141 P0161 |
Cumulative heater resistance correction value exceeds threshold (2 trip detection logic) |
|
HINT:
- For Bank 1 refers to the bank that includes No. 1 cylinder.
- For Bank 2 refers to the bank that does not include No. 1 cylinder.
- Sensor 1 refers to the sensor closest to the engine assembly.
- Sensor 2 refers to the sensor farthest away from the engine assembly.
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 determines that there is an open circuit in the heater. If the current is above the threshold value, the ECM determines that there is a short circuit in the heater.
The ECM constantly monitors the current applied to the heater. If the ECM detects an open or short circuit, the ECM turns the MIL on and stores a DTC.
If a malfunction is detected, the ECM cuts off the current applied to the heater.
Example:
The ECM stores 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 stored.
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 determines that there is a malfunction in the HO2 sensor heater and stores DTC P0141 or P0161.
MONITOR STRATEGY
|
Related DTCs |
P0037: Heated oxygen sensor heater (bank 1) range check (Low electrical current) P0038: Heated oxygen sensor heater (bank 1) range check (High electrical current) P0057: Heated oxygen sensor heater (bank 2) range check (Low electrical current) P0058: Heated oxygen sensor heater (bank 2) range check (High electrical current) P0141: Heated oxygen sensor heater performance (bank 1) P0161: Heated oxygen sensor heater performance (bank 2) |
|
Required Sensors/Components (Main) |
Heated oxygen sensor heater |
|
Required Sensors/Components (Related) |
- |
|
Frequency of Operation |
Continuous: P0037, P0038, P0057 and P0058 Once per driving cycle: P0141 and P0161 |
|
Duration |
0.5 seconds: P0037 and P0057 1 second: P0038 and P0058 (case 1) 2.048 seconds: P0038 and P0058 (case 2) 10 seconds: P0141 and P0161 |
|
MIL Operation |
Immediate: P0037, P0038, P0057 and P0058 2 driving cycles: P0141 and P0161 |
|
Sequence of Operation |
None |
TYPICAL ENABLING CONDITIONS
All
|
Monitor runs whenever following DTCs not present |
None |
P0037 and P0057
|
Battery voltage |
10.5 to 20 V |
P0038 and P0058 (case 1)
|
Battery voltage |
10.5 or more |
|
Engine |
Running |
|
Starter |
OFF |
P0038 and P0058 (case 2)
|
Battery voltage |
10.5 to 20 V |
|
Learned heater OFF current operation |
Completed |
P0141 or P0161 (Heater Performance Monitor Check)
|
All of following conditions met: |
- |
|
Battery voltage |
10.5 V or more |
|
Fuel cut |
OFF |
|
Time after fuel cut ON to OFF |
30 seconds or more |
|
Accumulated heater ON time |
100 seconds or more |
TYPICAL MALFUNCTION THRESHOLDS
P0037 and P0057
|
Heater current |
Less than 0.3 A |
P0038 and P0058 (case 1)
|
Heater current |
More than 2 A |
P0038 and P0058 (case 2)
|
Hybrid IC high current limiter port |
Fail |
P0141 or P0161 (Heater Performance Monitor Check)
|
Accumulated heater resistance |
Varies with sensor element temperature (Example: More than 23 Ω) |
COMPONENT OPERATING RANGE
|
Heated Oxygen (HO2) sensor heater current |
0.4 to 1 A (when engine idles, HO2 sensor warmed up and battery voltage 11 to 14 V) |
WIRING DIAGRAM
Refer to DTC P0136
.
CONFIRMATION DRIVING PATTERN
These DTCs are detected when the engine idles for 110 seconds or more.
INSPECTION PROCEDURE
HINT:
Sensor 2 refers to the sensor mounted behind the Three-Way Catalytic Converter (TWC) and located far from the engine assembly.
Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
PROCEDURE
|
1. |
INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE) |
(a) Disconnect the HO2 sensor connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
1 (HT1B) - 2 (+B) |
20°C (68°F) |
11 to 16 Ω |
|
1 (HT1B) - 4 (E1) |
Always |
10 kΩ or higher |
|
1 (HT2B) - 2 (+B) |
20°C (68°F) |
11 to 16 Ω |
|
1 (HT2B) - 4 (E1) |
Always |
10 kΩ or higher |
|
|
2. |
CHECK TERMINAL VOLTAGE (+B OF HO2 SENSOR) |
(a) Disconnect the HO2 sensor connector.
(b) Turn the ignition switch to ON.
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
|
Tester Connection |
Switch Condition |
Specified Condition |
|---|---|---|
|
D17-2 (+B) - Body ground |
Ignition switch ON |
11 to 14 V |
|
D18-2 (+B) - Body ground |
Ignition switch ON |
11 to 14 V |
Result
|
Result |
Proceed to |
|---|---|
|
Outside standard range |
A |
|
Within standard range |
B |
|
|
3. |
INSPECT INTEGRATION RELAY (EFI MAIN) |
(a) Remove the integration relay from the engine room relay block.
(b) Inspect the EFI NO. 1 fuse.
(1) Remove the EFI NO. 1 fuse from the integration relay.
(2) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
EFI NO. 1 fuse |
Always |
Below 1 Ω |
(3) Reinstall the EFI NO. 1 fuse.
(c) Inspect the EFI MAIN relay.
(1) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
1C-1 - 1B-4 |
When battery voltage not applied |
10 kΩ or higher |
|
When battery voltage applied to terminals 1B-2 and 1B-3 |
Below 1 Ω |
|
|
4. |
CHECK HARNESS AND CONNECTOR (HO2 SENSOR - INTEGRATION RELAY) |
(a) Check the EFI NO. 2 fuse.
(1) Remove the EFI NO. 2 fuse from the engine room relay block.
(2) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
EFI NO. 2 fuse |
Always |
Below 1 Ω |
(3) Reinstall the EFI NO. 2 fuse.
(b) Disconnect the HO2 sensor connector.
(c) Remove the integration relay from the engine room relay block.
(d) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
D17-2 (+B) - 1B-4 |
Always |
Below 1 Ω |
|
D18-2 (+B) - 1B-4 |
Always |
Below 1 Ω |
|
D17-2 (+B) or 1B-4 - Body ground |
Always |
10 kΩ or higher |
|
D18-2 (+B) or 1B-4 - Body ground |
Always |
10 kΩ or higher |
|
|
9. |
CHECK HARNESS AND CONNECTOR (HO2 SENSOR - ECM) |
(a) Disconnect the HO2 sensor connector.
(b) Disconnect the ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
|
Tester Connection |
Condition |
Specified Condition |
|---|---|---|
|
D17-1 (HT1B) - D56-45 (HT1B) |
Always |
Below 1 Ω |
|
D18-1 (HT2B) - D56-44 (HT2B) |
Always |
Below 1 Ω |
|
D17-1 (HT1B) or D56-45 (HT1B) - Body ground |
Always |
10 kΩ or higher |
|
D18-1 (HT2B) or D56-44 (HT2B) - Body ground |
Always |
10 kΩ or higher |
|
|
10. |
CHECK WHETHER DTC OUTPUT RECURS |
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream ON.
(d) Clear DTCs
.
(e) Start the engine.
(f) Allow the engine to idle for 2 minutes or more.
(g) Enter the following menus: Powertrain / Engine / Trouble Codes.
(h) Read DTCs.
Result
|
Result |
Proceed to |
|---|---|
|
No DTC is output |
A |
|
P0037, P0038, P0057, P0058, P0141 and/or P0161 are output |
B |
|
|
|