P0037
1AR-FE ENGINE CONTROL: SFI SYSTEM: P0037,P0038,P0141,P102D: Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2)
DESCRIPTION
Refer to DTC P0136 P0136.
HINT
* Sensor 2 refers to the sensor mounted behind the three-way catalytic converter and located far from the engine assembly.
* When any of these DTCs is stored, the ECM enters fail-safe mode. The ECM turns off the heated oxygen sensor heater in fail-safe mode. Fail-safe mode continues until the ignition switch is turned off.
* The ECM provides a pulse width modulated control circuit to adjust the current through the heater. The heated oxygen sensor heater circuit uses a relay on the +B side of the circuit.
HINT
* 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 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 and P102D):
The ECM monitors the current applied to the heated oxygen sensor heater to check the heater for malfunctions.
If the heater current is outside the normal range, the signal transmitted by the heated oxygen sensor becomes inaccurate. When the current in the heated oxygen sensor heater is outside the normal operating range, the ECM interprets this as a malfunction in the sensor heater and stores a DTC.
Heated Oxygen Sensor Heater Performance (P0141):
After the accumulated heater ON time exceeds 100 seconds, the ECM calculates the heater resistance using 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 heated oxygen sensor heater and stores DTC P0141.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
P0037 (Case 1)
P0037 (Case 2)
P0038
P0141
P102D
TYPICAL MALFUNCTION THRESHOLDS
P0037 (Case 1)
P0037 (Case 2)
P0038
P0141
P102D
COMPONENT OPERATING RANGE
MONITOR RESULT
- Refer to Checking Monitor Status Mode 6 Data.
CONFIRMATION DRIVING PATTERN
1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON and turn the Techstream on.
3. Clear DTCs (even if no DTCs are stored, perform the clear DTC procedure).
4. Turn the ignition switch off and wait for at least 30 seconds.
5. Turn the ignition switch to ON and turn the Techstream on [A].
6. Start the engine and idle it for 5 minutes or more [B].
7. With the vehicle stationary, depress the accelerator pedal and maintain an engine speed of 3000 rpm for 1 minute [C].
8. Idle the engine for 5 minutes or more [D].
9. Enter the following menus: Powertrain / Engine / Trouble Codes [E].
10. Read pending DTCs.
HINT
* If a pending DTC is output, the system is malfunctioning.
* If a pending DTC is not output, perform the following procedure.
11. Enter the following menus: Powertrain / Engine / Utility / All Readiness.
12. Input the DTC: P0037, P0038, P0141 or P102D.
13. Check the DTC judgment result.
HINT
* If the judgment result shows NORMAL, the system is normal.
* If the judgment result shows ABNORMAL, the system has a malfunction.
* If the judgment result shows INCOMPLETE or UNKNOWN, perform steps [B] through [E] again.
14. If no pending DTC is output, perform a universal trip and check for permanent DTCs DTC Check / Clear.
HINT
* If a permanent DTC is output, the system is malfunctioning.
* If no permanent DTC is output, the system is normal.
WIRING DIAGRAM
Refer to DTC P0031 P0031.
INSPECTION PROCEDURE
NOTICE:
Inspect the fuses for circuits related to this system before performing the following 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 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) Inspect the heated oxygen sensor Component Tests and General Diagnostics.
NG -- REPLACE HEATED OXYGEN SENSOR Removal
OK -- Continue to next step.
2. CHECK TERMINAL VOLTAGE (POWER SOURCE OF HEATED OXYGEN SENSOR)
(a) Disconnect the heated oxygen sensor connector.
(b) Turn the ignition switch to ON.
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
Text in Illustration
(d) Reconnect the heated oxygen sensor connector.
NG -- INSPECT A/F HTR RELAY
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)
(a) Disconnect the heated oxygen sensor connector.
(b) Disconnect the ECM connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance (Check for Open):
Standard Resistance (Check for Short):
(d) Reconnect the heated oxygen sensor connector.
(e) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. CHECK WHETHER DTC OUTPUT RECURS (DTC P0037, P0038, P0141 OR P102D)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Clear DTCs DTC Check / Clear.
(e) Start the engine.
(f) Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
(g) Enter the following menus: Powertrain / Engine / Trouble Codes.
(h) Read pending DTCs.
Result
B -- REPLACE ECM Removal
A -- CHECK FOR INTERMITTENT PROBLEMS Check for Intermittent Problems
5. INSPECT A/F HTR RELAY
(a) Inspect the A/F HTR relay Testing and Inspection.
NG -- REPLACE A/F HTR RELAY
OK -- Continue to next step.
6. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - A/F HTR RELAY)
(a) Disconnect the heated oxygen sensor connector.
(b) Remove the A/F HTR relay from the engine room relay 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) Reconnect the heated oxygen sensor connector.
(e) Reinstall the A/F HTR relay.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- CHECK ECM POWER SOURCE CIRCUIT Component Tests and General Diagnostics