P0037

2TR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0037,P0038,P0141: Oxygen Sensor Heater Control Circuit Low (Bank 1 Sensor 2)


CAUTION / NOTICE / HINT

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 concentration 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 and P0038):

- The ECM monitors the current applied to the HO2 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 stores DTC P0038 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 is stored.

Heated oxygen sensor heater performance (P0141):

- 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 heated oxygen sensor heater and sets DTC P0141.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

All:





P0037:





P0038 (Case 1):





P0038 (Case 2):





P0141:





TYPICAL MALFUNCTION THRESHOLDS

P0037:





P0038:





P0141 (Heater performance monitor check):





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 and ECT / 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 and ECT / Utility / All Readiness.

12. Input the DTC: P0037, P0038 or P0141.

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
* If other DTCs relating to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.
* 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.
* When the values for the Data List items O2 Heater Curr Val B1S2 is not 0 A, the heater is on.
* Refer to "Data List / Active Test" [O2 Heater B1S2 and O2 Heater Curr Val B1S2 Data List / Active List.
* Sensor 1 refers to the sensor closest to the engine assembly.
* Sensor 2 refers to the sensor farthest away from the engine assembly.

PROCEDURE

1. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)

(a) Inspect the heated oxygen sensor Heated Oxygen Sensor.

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 EFI 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 OR P0141)

(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 and ECT / Trouble Codes.

(h) Read pending DTCs.

Result





B -- REPLACE ECM Removal

A -- CHECK FOR INTERMITTENT PROBLEMS Check for Intermittent Problems

5. INSPECT EFI RELAY

(a) Inspect the EFI relay Component Tests and General Diagnostics.

NG -- REPLACE EFI RELAY
OK -- Continue to next step.

6. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - EFI RELAY)

(a) Disconnect the heated oxygen sensor connector.

(b) Remove the EFI 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 EFI relay.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- CHECK ECM POWER SOURCE CIRCUIT Component Tests and General Diagnostics