DTC Logic

DTC DETECTION LOGIC

To judge the malfunction of A/F sensor 1, this diagnosis measures response time of the A/F signal computed by ECM from the A/F sensor 1 signal. The time is compensated by engine operating (speed and load), fuel feedback control constant, and the A/F sensor 1 temperature index. Judgment is based on whether the compensated time (the A/F signal cycling time index) is inordinately long or not.

DTC CONFIRMATION PROCEDURE

1.PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at least 10 seconds before conducting the next test.

TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 11 V at idle.

Do you have CONSULT-III? YES >> GO TO 2.

NO >> GO TO 5.

2.PERFORM DTC CONFIRMATION PROCEDURE-I

With CONSULT-III

1. Start engine and warm it up to normal operating temperature.

2. Turn ignition switch OFF and wait at least 10 seconds.

3. Restart engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1minute under no load.

4. Let engine idle for 1 minute.

5. Select “ENGINE” using CONSULT-III.

6. Select “A/F SEN1(B1) P1278/P1279” (for DTC P0133) of “A/F SEN1” in “DTC WORK SUPPORT” mode.

7. Touch “START”.

Is “COMPLETED” displayed on CONSULT-III screen? YES >> GO TO 3 NO >> GO TO 4.

3.PERFORM DTC CONFIRMATION PROCEDURE-II

Touch “SELF-DIAG RESULT”.

Which is displayed on CONSULT-III screen? OK >> INSPECTION END

NG >> Go to EC-611, "Diagnosis Procedure".

4.PERFORM DTC CONFIRMATION PROCEDURE-II

1. After perform the following procedure, “TESTING” will be displayed on the CONSULT-III screen.

- Increase the engine speed up to between 4,000 and 5,000 rpm and maintain that speed for 10 seconds.

- Fully release accelerator pedal and then let engine idle for about 10 seconds.

If “TESTING” is not displayed after 10 seconds, refer to EC-558, "Component Function Check".

2. Wait for about 20 seconds at idle under the condition that “TESTING” is displayed on the CONSULT-III screen.

3. Make sure that “TESTING” changes to “COMPLETED”.

If “TESTING” changed to “OUT OF CONDITION”, refer to EC-558, "Component Function Check".

4. Touch “SELF-DIAG RESULT”.

Which is displayed on CONSULT-III screen? OK >> INSPECTION END

NG >> Go to EC-611, "Diagnosis Procedure".

5.CHECK AIR-FUEL RATIO SELF-LEARNING VALUE

With GST

1. Start engine and warm it up to normal operating temperature.

2. Select Service $01 with GST.

3. Calculate the total value of “Short term fuel trim” and “Long term fuel trim” indications.

Is the total percentage within ±15%? YES >> GO TO 7.

NO >> GO TO 6.

6.DETECT MALFUNCTIONING PART

Check the following.

• Intake air leaks
• Exhaust gas leaks
• Incorrect fuel pressure • Lack of fuel
• Fuel injector
• Incorrect PCV hose connection • PCV valve
• Mass air flow sensor

>> Repair or replace malfunctioning part.

7.PERFORM DTC CONFIRMATION PROCEDURE

1. Turn ignition switch OFF and wait at least 10 seconds.

2. Restart engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1minute under no load.

3. Let engine idle for 1 minute.

4. Increase the engine speed up to between 4,000 and 5,000 rpm and maintain that speed for 10 seconds.

5. Fully release accelerator pedal and then let engine idle for about 1 minute.

6. Check 1st trip DTC.

Is 1st trip DTC detected? YES >> Go to EC-611, "Diagnosis Procedure".

NO >> INSPECTION END

Diagnosis Procedure

1.CHECK GROUND CONNECTION

1. Turn ignition switch OFF.

2. Check ground connection E21 and E38. Refer to Ground Inspection in GI-44, "Circuit Inspection".

Is the inspection result normal? YES >> GO TO 2.

NO >> Repair or replace ground connection.

2.RETIGHTEN A/F SENSOR 1

Loosen and retighten the A/F sensor 1. Refer to EM-166, "Exploded View".

>> GO TO 3.

3.CHECK EXHAUST GAS LEAK

1. Start engine and run it at idle.

2. Listen for an exhaust gas leak before three way catalyst 1.

Is exhaust gas leak detected? YES >> Repair or replace.

NO >> GO TO 4.

4.CHECK FOR INTAKE AIR LEAK

Listen for an intake air leak after the mass air flow sensor.

Is intake air leak detected? YES >> Repair or replace.

NO >> GO TO 5.

5.CLEAR THE MIXTURE RATIO SELF-LEARNING VALUE

1. Clear the mixture ratio self-learning value. Refer to EC-546, "Work Procedure".

2. Run engine for at least 10 minutes at idle speed.

Is the 1st trip DTC P0171 or P0172 detected? Is it difficult to start engine? YES >> Perform trouble diagnosis for DTC P0171 or P0172. Refer to EC-635, "DTC Logic" or EC-639, "DTC Logic".

NO >> GO TO 6.

6.CHECK AIR FUEL RATIO (A/F) SENSOR 1 POWER SUPPLY CIRCUIT

1. Disconnect A/F sensor 1 harness connector.

2. Turn ignition switch ON.

3. Check the voltage between A/F sensor 1 harness connector and ground.

Is the inspection result normal? YES >> GO TO 8.

NO >> GO TO 7.

7.DETECT MALFUNCTIONING PART

Check the following.

• Harness connectors E8, F1 • IPDM E/R harness connector E14 • 20A fuse (No. 43)
• Harness for open or short between A/F sensor 1 and fuse

>> Repair or replace harness or connectors.

8.CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1. Turn ignition switch OFF.

2. Disconnect ECM harness connector.

3. Check the continuity between A/F sensor 1 harness connector and ECM harness connector.

4. Check the continuity between A/F sensor 1 harness connector and ground or ECM harness connector and ground.

5. Also check harness for short to power.

Is the inspection result normal? YES >> GO TO 9.

NO >> Repair open circuit, short to ground or short to power in harness or connectors.

9.CHECK AIR FUEL RATIO (A/F) SENSOR 1 HEATER

Refer to EC-578, "Component Inspection".

Is the inspection result normal? YES >> GO TO 10.

NO >> GO TO 13.

10.CHECK MASS AIR FLOW SENSOR

Check both mass air flow sensor.

Refer to EC-590, "Component Inspection".

Is the inspection result normal? YES >> GO TO 11.

NO >> Replace malfunctioning mass air flow sensor.

11.CHECK PCV VALVE

Refer to EC-804, "Inspection".

Is the inspection result normal? YES >> GO TO 12.

NO >> Repair or replace PCV valve.

12.CHECK INTERMITTENT INCIDENT

Perform GI-42, "Intermittent Incident".

Is the inspection result normal? YES >> GO TO 13.

NO >> Repair or replace.

13.REPLACE AIR FUEL RATIO (A/F) SENSOR 1

Replace malfunctioning air fuel ratio (A/F) sensor 1.

CAUTION:
• Discard any A/F sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a hard surface such as a concrete floor; use a new one.

• Before installing new A/F sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner (commercial service tool) and approved anti-seize lubricant (commercial service tool).

>> INSPECTION END