P0038

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

DESCRIPTION

Refer to DTC P0136 P0136.

HINT
* When any of these DTCs are set, 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 uses pulse width modulation to adjust the current through the heater. The heated oxygen sensor heater circuit uses a relay on the +B side of the circuit.

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 and P0038):

The ECM monitors the current applied to the heated oxygen 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 when the current in the heated oxygen sensor heater is more than 2 A. Conversely, when the heater current is less than 0.3 A, DTC P0037 is set.

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 will determine that there is a malfunction in the heated oxygen sensor heater and set DTC P0141.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

All

P0037

P0038 (Case 1)

P0038 (Case 2 and 3)

P0141

HINT
When the values for the Data List items O2 Heater Curr Val B1S2 is not 0 A, the heater is on.

TYPICAL MALFUNCTION THRESHOLDS

P0037

P0038 (Case 1 and 2)

P0038 (Case 3)

P0141

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 the DTCs (even if no DTCs are stored, perform the clear DTC operation) Reading and Clearing Diagnostic Trouble Codes.

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 the 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.

14. If the judgment result shows INCOMPLETE or UNKNOWN, perform steps [B] through [E] again.

15. If no pending DTC is output, perform a universal trip and check for permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

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 P0136 P0136.

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.
* 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 Component Tests and General Diagnostics.

NG -- REPLACE HEATED OXYGEN SENSOR Removal
OK -- Continue to next step.

2. CHECK TERMINAL VOLTAGE (POWER SOURCE)

(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:

(d) Reconnect the heated oxygen sensor connector.

NG -- INSPECT FUSE (EFI NO. 1 FUSE)
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 (HEATED OXYGEN SENSOR - ECM)
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 Reading and Clearing Diagnostic Trouble Codes.

(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 / Pending.

(h) Read the DTCs.

Result:

B -- REPLACE ECM Removal

A -- CHECK FOR INTERMITTENT PROBLEMS Check for Intermittent Problems

5. INSPECT FUSE (EFI NO. 1 FUSE)

(a) Remove the EFI No.1 fuse from the engine room relay block.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

(c) Reinstall the EFI No. 1 fuse.

NG -- REPLACE FUSE (EFI NO. 1)

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (INTEGRATION RELAY (EFI MAIN RELAY) - HEATED OXYGEN SENSOR)