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P0031





2GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0031, P0032, P0051, P0052, P101D, P103D: Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)
P103D - A/F Sensor Heater Circuit Performance Bank 2 Sensor 1 Stuck ON

DESCRIPTION

Refer to DTC P2195 P2195.

HINT
- When any of these DTCs are set, the ECM enters fail-safe mode. The ECM turns off the A/F sensor heater in fail-safe mode. Fail-safe mode continues until the engine switch is turned off.
- The ECM provides a pulse width modulated control circuit to adjust the current through the heater. The A/F sensor heater circuit uses a relay on the +B side of the circuit.










MONITOR DESCRIPTION

The ECM uses information from the air fuel ratio sensor to regulate the air fuel ratio and keep it close to the stoichiometric level. This maximizes the ability of the three-way catalytic converter to purify the exhaust gases.

The air fuel ratio sensor detects oxygen levels in the exhaust gas and transmits the information to the ECM. The inner surface of the sensor element is exposed to the outside air. The outer surface of the sensor element is exposed to the exhaust gas. The sensor element is made of platinum-coated zirconia and includes an integrated heating element.

The zirconia element generates a small voltage when there is a large difference in the oxygen concentrations between the exhaust gas and outside air. The platinum coating amplifies this voltage generation.

The air fuel ratio sensor is more efficient when heated. When the exhaust gas temperature is low, the sensor cannot generate useful voltage signals without supplementary heating. The ECM regulates the supplementary heating using a duty-cycle approach to adjust the average current in the sensor heater element. If the heater current is outside the normal range, the signal transmitted by the air fuel ratio sensor becomes inaccurate. As a result, the ECM is unable to regulate the air fuel ratio properly.

When the current in the air fuel ratio sensor heater is outside the normal operating range, the ECM interprets this as a malfunction in the sensor heater and stores a DTC.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

All





P0031 and P0051





P0032 and P0052





P101D and P103D





TYPICAL MALFUNCTION THRESHOLDS

P0031 and P0051





P0032 and P0052





P101D and P103D





COMPONENT OPERATING RANGE

P0031 and P0051:





P0032 and P0052:





P101D and P103D:





CONFIRMATION DRIVING PATTERN





1. Connect the Techstream to the DLC3.

2. Turn the engine switch on (IG) and turn the Techstream on.

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

4. Turn the engine switch off and wait for 30 seconds.

5. Turn the engine switch on (IG) 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.

10. Read the DTC [E].

11. If a DTC is output, the system is malfunctioning.

HINT
If a DTC is not output, perform the following procedure.

12. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

13. Input the DTC: P0031, P0032, P0051, P0052, P101D or P103D.

14. Check the DTC judgment result.





HINT
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows NORMAL, the system is normal.
- If the judgment result shows INCOMPLETE or N/A, perform step [B] through [D] again.

15. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

16. Check the judgment result.

HINT
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows NORMAL, the system is normal.

17. If the test result is INCOMPLETE or N/A and no 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 P2195 P2195.

INSPECTION PROCEDURE

NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

HINT
- Bank 1 refers to the bank that includes the No. 1 cylinder*.
*: The No. 1 cylinder is the cylinder which is farthest from the transaxle.
- Bank 2 refers to the bank that does not include the 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.
- 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.
- Change the fuel injection volume using the Control the Injection Volume function provided in the Active Test and monitor the air fuel ratio sensor output voltage P0136. If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

PROCEDURE

1. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

(a) Inspect the A/F sensor Air Fuel Ratio Sensor.

NG -- REPLACE AIR FUEL RATIO SENSOR Removal
OK -- Continue to next step.

2. CHECK TERMINAL VOLTAGE (+B OF A/F SENSOR)

(a) Disconnect the B3 or B4 A/F sensor connector.





(b) Turn the engine switch on (IG).

(c) Measure the voltage between the terminals of the A/F sensor connector and body ground.

Standard voltage:





OK -- CHECK HARNESS AND CONNECTOR
NG -- Continue to next step.

3. INSPECT ENGINE ROOM JUNCTION BLOCK (EFI RELAY, A/F RELAY)

(a) Inspect the EFI relay Testing and Inspection.

(b) Inspect the A/F relay Testing and Inspection.

NG -- REPLACE ENGINE ROOM JUNCTION BLOCK
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (A/F SENSOR - A/F RELAY)

(a) Disconnect the B3 or B4 A/F sensor connector.

(b) Remove the engine room junction block from the engine room R/B.

(c) Measure the resistance between the terminals.

Standard resistance (Check for open):





Standard resistance (Check for short):





(d) Reinstall the engine room junction block.

(e) Reconnect the A/F sensor connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- CHECK ECM POWER SOURCE CIRCUIT ECM Power Source Circuit

5. CHECK HARNESS AND CONNECTOR

(a) Disconnect the B3 or B4 A/F sensor connector.

(b) Disconnect the B12 ECM connector.

(c) Measure the resistance between the terminals.

Standard resistance (Check for open):





Standard resistance (Check for short):





(d) Reconnect the ECM connector.

(e) Reconnect the A/F sensor connectors.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

6. CHECK WHETHER DTC OUTPUT RECURS

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.

(e) Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

(f) Enter the following menus: Powertrain / Engine / Trouble Codes.

(g) Read the DTCs.

Result:





B -- REPLACE ECM Removal

A -- CHECK FOR INTERMITTENT PROBLEMS Check for Intermittent Problems
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