Inspection Procedure

WARNING: This page is about a different car, the 2004 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.

HINT:

Hand-held tester only:

The narrowing down the trouble area is possible by performing ACTIVE TEST of the following" A/F CONTROL" (Heated oxygen sensor or another can be distinguished).

Perform ACTIVE TEST by hand-held tester (A/F CONTROL).

HINT:

"A/F CONTROL: is the ACTIVE TEST which changes the injection volume to -12.5% or +25%.

Connect the hand-held tester to the DLC3 on the vehicle.
Turn the ignition switch ON.
Warm up the engine with the engine speed at 2,500 RPM for approximately 90 seconds.
Select the item "DIAGNOSIS/ENHANCED OBD II/ACTIVE TEST/A/F/ CONTROL".
Perform "A/F CONTROL" with the engine in an idle condition (press the right or left button).

RESULT:

Heated oxygen sensor reacts in accordance with increase and decrease of injection volume

+25 % -> rich output: More than 0.5 V

-12.5 % -> lean output: Less than 0.4 V

NOTE: However, there is a few seconds delay in the sensor 1 (front sensor) output. And there is about 20 seconds delay in the sensor 2 rear sensor).

Fig 1: Heated Oxygen Sensors Output Voltage Chart

The following A/F CONTROL procedure enables the technician to check and graph the voltage output of the heated oxygen sensors (sensor 1 and 2).

For displaying the graph indication, enter "ACTIVE TEST/A/F CONTROL/USER DATA" then select "O2S B1S1 and O2S B1S2" by pressing "YES" button and push "ENTER" button before pressing "F4" button.

HINT:

If different DTCs related to different systems that have terminal E2 as the ground terminal, terminal E2 may be open.
Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.
A high heated oxygen sensor (sensor 1) voltage (0.5 V or more) could be caused by a rich air fuel mixture. Check for conditions that would cause the engine to run rich.
A low heated oxygen sensor (sensor 1) voltage (0.5 V or less) could be caused by a lean air fuel mixture. Check for conditions that would cause the engine to run lean.

Check air induction system (See SFI SYSTEM ).
CHECK:

Check the air induction system for vacuum leaks.
1. NG: Repair or replace air induction system.
2. OK: Go to next step.
Check connection of PCV piping.
1. NG: Repair or replace PCV valve and hose.
2. OK: Go to next step.
Check injector injection (See INSPECTION )
1. NG: Replace injector.
2. OK: Go to next step.
Check mass air flow sensor.
PREPARATION:

Remove the mass air flow meter.

CHECK:
1. Inspect output voltage.
  1. Apply battery voltage across terminals +B and E2G.
  2. Connect the positive (+) tester prove to terminal VG, and negative (-) tester prove to terminal E2G.
  3. Blow air into the mass air flow sensor, and check that the voltage fluctuates.
2. Inspect resistance.
  1. Measure the resistance between terminals of the intake air temperature sensor.
    Resistance:
    
    Fig 2: Measuring Resistance Between Terminals
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    
    Fig 3: Terminal Resistance Chart
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG: Repair or replace mass air flow meter.
2. OK: Go to next step.
Check engine coolant temperature sensor.
PREPARATION:

Remove the engine coolant temperature sensor.

CHECK:
1. Measure the resistance between the terminals of the engine coolant temperature sensor.
  Resistance:
  
  Fig 4: Measuring Resistance Between Terminals
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 5: Terminal Resistance Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  NOTE: In case of checking the engine coolant temperature sensor in the water, be careful not to allow water to go into the terminals. After checking, dry the sensor.
  
  HINT:
  
  Alternate procedure: Connect an ohmmeter to the installed engine coolant temperature sensor and read the resistance. Use an infrared thermometer to measure the engine temperature in the immediate vicinity of the sensor. Compare these values to the resistance/temperature graph. Change the engine temperature (warm up or allow to cool down) and repeat the test.
2. Reinstall the engine coolant temperature sensor.
1. NG: Repair or replace engine coolant temperature sensor.
2. OK: Go to next step.
Check for spark and ignition (See IGNITION SYSTEM ).
1. NG: Repair or replace.
2. OK: Go to next step.
Check fuel pressure (See FUEL PUMP ).
CHECK:

Check the fuel pressure (high or low pressure).
1. NG: check and repair fuel pump, pressure regulator, fuel pipe line and filter (See SFI SYSTEM ).
2. OK: Go to next step.
Check gas leakage on exhaust system.
1. NG: Repair or replace exhaust gas leakage point.
2. OK: Go to next step.
Check output voltage of heated oxygen sensor (bank 1, 2 sensor 1) during idling.
PREPARATION:
1. Connect the OBD II scantool or hand-held tester to the DLC3.
2. Warm up the engine to normal operating temperature (above 75°C (169°F)).
3. Enter the following menu: DIAGNOSIS / ENHANCED OBD II / DATA LIST / 02S B1 S1 OR B2 S1.
CHECK:

Use the OBD II scan tool or hand-held tester to read an output voltage of the heated oxygen sensor during idling.

OK:

Heated oxygen sensor output voltage:

Alternates repeatedly between less than 0.4 V and more than 0.55 V (See the following table).

Fig 6: Identifying Heated Oxygen Sensor Output Voltage
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. OK: Go to step 17 .
2. NG: Go to next step.
Check resistance of heated oxygen sensor heater (See INSPECTION )
1. NG: Replace heated oxygen sensor.
2. OK: Go to next step.
Check EFI relay (See EFI MAIN RELAY )
1. NG: Replace EFI relay.
2. OK: Go to next step.
Check for open and short in harness and connector between ECM and heated oxygen sensor (bank 1, 2 sensor 1) (See ).

Fig 7: Bank 1 And Sensor 1 System Drawing Circuit Diagram
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG: Repair or replace harness or connector.
2. OK: Go to next step.
Replace heated oxygen sensor.
1. GO: Go to next step.
Perform confirmation driving pattern.

Fig 8: Perform Confirmation Driving Pattern
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. Disconnect the battery terminal and wait for a minute (clear learning value of the air fuel ratio). (*1)
2. Connect the hand-held tester to the DLC3. (*1)
3. Switch the hand-held tester from the normal mode to the check mode (See PRE-CHECK ). (*1)
4. Start the engine and let it idle until engine coolant temperature is 75 °C (167 °F) or more. (*2)
5. Drive the vehicle at 50 mph (30 km/h) or more for 3 minutes or more. (*3)
6. Let the engine idle for approx. 2 minutes. (*4)
7. Perform steps (e) and (g) at least 3 times.
HINT:

If a malfunction exists, the MIL will be illuminated during step (f).

NOTE: If the conditions in this test are not strictly followed, detecting a malfunction may be difficult. If you do not have a hand-held tester, turn the ignition switch OFF after performing steps (e) to (f), and then do step (f) again.
1. GO: Go to next step.
Is there DTC P0171, P0172, P0174 or P0175 being output again?
1. Yes: Replace ECM (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ) and perform confirmation driving pattern (Refer to step 14 ).
2. NO: Go to next step.
Did vehicle run out of fuel in past?
1. NO: Check for Intermittent problems (See PRE-CHECK ).
2. YES: DTC P0171, P0172, P0174, P0175 is caused by running out of fuel.
Perform confirmation driving pattern.
HINT:

Clear all DTCs prior to performing the confirmation driving pattern (Refer to step 14).
1. GO: Go to next step.
Is there DTC P0171, P0172, P0174 and/or P0175 being output again?
1. NO: Go to step 22 .
2. YES: Go to next step.
Replace heated oxygen sensor.
1. GO: Go to next step.
Perform confirmation driving pattern.
HINT:

Clear all DTCs prior to performing the confirmation driving pattern (Refer to step 14).
1. GO: Go to next step.
Is the DTC P0171, P0172, P0174 and/or P0175 being output again?
1. YES: Replace ECM (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ) and perform confirmation driving pattern (Refer to step 14 ).
2. NO: Go to next step.
Confirm if vehicle has run out of fuel in past.
1. NO: Check for intermittent problems. (See PRE-CHECK ).
2. YES: DTC is caused by running out of fuel (DTCs P0171, P0172 P0174 and/or P0175).