Engine Controls - Self-Diagnostics: Diagnosis Lexus ES XV30 facelift

MALFUNCTION INDICATOR LIGHT (MIL) INSPECTION

Note. The CHECK engine light located on instrument cluster is known as Malfunction Indicator Light (MIL). Inspect MIL to ensure it is operational and will come on if a Diagnostic Trouble Code (DTC) is set.

1. Turn ignition on with engine off. MIL should come on and remain on. If MIL does not come on, check bulb circuit on instrument cluster and wiring circuit between MIL and ECM. See appropriate WIRING DIAGRAMS article.
2. Start engine and ensure MIL goes off. If MIL remains on with engine running, a malfunction is detected. Proceed to «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-151771-S23177868752003010800000) .

TESTING PROCEDURE

To ensure correct diagnosis and repair, testing should be done in the following sequence

1. Record Customer Complaint Ensure all customer complaints or observations are recorded. Test drive vehicle with customer, when necessary, for malfunction verification.
2. Retrieve Diagnostic Trouble Codes & Freeze Frame Data Connect appropriate OBD-II scan tool. Retrieve codes and record any freeze-frame data. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-151771-S23177868752003010800000) .
3. Clear Trouble Codes & Freeze Frame Data Clear codes using scan tool. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-151771-S35110467932003010800000) .
4. Perform Visual Inspection Inspect all connectors of suspect circuit or component. Ensure all connections are clean and tight.
5. Confirm Symptoms & Trouble Codes Perform road test. Determine if original symptoms are still present. Note 2 trip logic. See «TWO-TRIP DETECTION LOGIC»(ref-151771-S29560308312003010800000) under INTRODUCTION. Retrieve codes.
6. Diagnose & Repair Diagnostic Trouble Codes Perform diagnosis and repair procedures as needed. See «DIAGNOSTIC TESTS»(ref-151771-S05031341802003010800000) . If no codes are present, proceed to «TROUBLE SHOOTING - NO CODES»(ref-151782) article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
7. Verification Procedure After repairs have been completed, clear all diagnostic trouble codes. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-151771-S35110467932003010800000) . Perform road test. Ensure no codes are present and all symptoms and/or complaints have been repaired.

RETRIEVING DIAGNOSTIC TROUBLE CODES

Note. Diagnostic Trouble Codes (DTCs) may be retrieved using Lexus scan tool or On-Board Diagnostic (OBD-II) scan tool that complies with SAE standard J-1978. Lexus scan tool or OBD-II scan tool may be operated in NORMAL mode when retrieving trouble codes. If no DTCs are retrieved in NORMAL mode, Lexus scan tool may be operated in CHECK mode, or OBD-II J1979-compliant scan tool may be used in CONTINUOUS TEST RESULTS function under MODE 7 to observe current data. For aftermarket scan tool, see owner's manual for instructions.

NORMAL mode is used to retrieve DTCs from Engine Control Module (ECM). CHECK mode (or CONTINUOUS TEST RESULTS function under MODE 7) is used to check for DTCs when operating vehicle to simulate conditions in which DTC was set, and contains a higher sensing ability to detect malfunctions. It is also useful to help determine malfunctions caused by poor electrical connections, which are difficult to determine using NORMAL mode.

Note. If using Lexus scan tool, when ignition is turned from ON to ACC or OFF position, or scan tool is switched from NORMAL mode to CHECK mode, all DTCs and freeze-frame data will be erased. DO NOT switch modes until all DTCs and freeze-frame data are recorded.

CHECK Mode Code Retrieval (Lexus Scan Tool Only)

1. Ensure vehicle battery is fully charged (at least 11 volts). Apply parking brake. Shift transmission/transaxle into Neutral (M/T) or Park (A/T). Turn A/C and all accessories off. Ensure throttle is in idle position.
2. Turn ignition off. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 DLC No. 3 connector is located under left side of instrument panel. Turn ignition on with engine off. Turn scan tool on.
3. Switch scan tool from NORMAL mode to CHECK mode. CHECK mode is operational if MIL on instrument cluster flashes. Start engine. Ensure MIL goes off. Try to simulate conditions of driveability complaint described by customer. NOTE: If ignition is turned from ON to ACC or OFF position, all DTCs and freeze-frame data will be erased. DO NOT switch modes until all DTCs and freeze-frame data are recorded.
4. Record any DTCs and freeze-frame data displayed for system diagnosis. If driveability problem exists and no codes are present, go to «TROUBLE SHOOTING - NO CODES»(ref-151782) article for diagnosis by symptom.
5. If any DTCs are present, perform appropriate circuit test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-151771-S42936466852003101500000). For more information on freeze-frame data, see «FREEZE-FRAME DATA»(ref-151771-S28640320182003010800000) under INTRODUCTION. For information on 2-trip detection logic codes, see «TWO-TRIP DETECTION LOGIC»(ref-151771-S29560308312003010800000) under INTRODUCTION.
6. After repairs for DTC have been completed, DTC must be cleared from ECM memory. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-151771-S35110467932003010800000).

CLEARING DIAGNOSTIC TROUBLE CODES

1. After performing repairs, clear ECM memory of all stored Diagnostic Trouble Codes (DTCs) and freeze-frame data. DTCs and freeze-frame data may be cleared by using scan tool and following scan tool manufacturer's instructions. NOTE: If using Lexus Scan Tool, DTCs and freeze-frame data may be cleared by switching from CHECK mode to NORMAL mode or from NORMAL mode to CHECK mode.
2. DTCs and freeze-frame data may also be cleared by removing EFI fuse from fuse/relay box located in engine compartment. DTCs and freeze-frame data may also be cleared by disconnecting negative battery cable. However, other memory functions (clock, radio, alarm, seats, etc.) will be cancelled and must be reset.

TROUBLE CODE TEST DRIVE CONFIRMATION

1. On certain Diagnostic Trouble Codes (DTCs), once DTC has been cleared from ECM memory, a DTC test drive confirmation test can be performed to verify repairs made and that DTC does not reset. The test drive confirmation test will duplicate the conditions required to set specified DTCs.
2. Test drive confirmation test lists the procedure to be performed to check that DTC does not reset, and applies only to specific DTCs. Test drive confirmation test will be included with proper DTC diagnostic test.

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DLC NO. 3 INSPECTION

1. If scan tool displays UNABLE TO CONNECT TO VEHICLE when scan tool is connected, try scan tool on another vehicle. If scan tool operates on another vehicle, go to next step. If scan tool does not operate on another vehicle, problem is probably with scan tool.
2. Check DLC No. 3 for loose or damaged terminals. Ensure DLC No. 3 terminals are in correct position in connector. See appropriate WIRING DIAGRAMS article. Repair as necessary. If connector and terminals are okay, go to next step.
3. Check voltage and resistance between ground and specified terminal on DLC No. 3. See «DLC NO. 3 VOLTAGE & RESISTANCE SPECIFICATIONS»(ref-151771-S01669074582003010800000) table. (Scheme 21) If voltage and resistance readings are not as specified, check wiring circuit. See appropriate WIRING DIAGRAMS article.

DLC NO. 3 VOLTAGE & RESISTANCE SPECIFICATIONS

Scheme 21

DIAGNOSTIC TESTS

Diagnosis & Repair (With Hand-Held Tester)

For wiring diagram (Scheme 22) For diagnosis and repair (Scheme 23)and (Scheme 24).

Scheme 22

Scheme 23

Scheme 24

Diagnosis & Repair (With OBDII Scan Tool)

For wiring diagram (Scheme 22) For diagnosis and repair (Scheme 25)and (Scheme 26).

Scheme 25

Scheme 26

For wiring diagram (Scheme 22) For diagnosis and repair (Scheme 27)- (Scheme 29).

Scheme 27

Scheme 28

Scheme 29

Diagnosis & Repair (With OBD-II Scan Tool)

For wiring diagram (Scheme 22) For diagnosis and repair (Scheme 30)- (Scheme 32).

Scheme 30

Scheme 31

Scheme 32

Diagnosis & Repair

For wiring diagram (Scheme 33) Check valve timing (check for loose and jumping teeth of timing belt). If faulty, adjust valve timing. If OK, check and replace ECM.

Scheme 33

For wiring diagram (Scheme 34) For diagnosis and repair (Scheme 35)

Scheme 34

Scheme 35

For wiring diagram (Scheme 36) For diagnosis and repair (Scheme 37)

Scheme 36

Scheme 37

For wiring diagram (Scheme 38) For diagnosis and repair (Scheme 39)- (Scheme 41).

Scheme 38

Scheme 39

Scheme 40

Scheme 41

Circuit Description

For circuit description, see Circuit Description under DTCs P0100, P0102 & P0103.

DTC P0101 is set when engine speed is less than 900 RPM (2 trip detection logic), throttle valve remains fully closed, mass air flow meter output is greater than 2.2 volts and THW is 158°F (70°C) or more for 10 seconds or more. It is also set when engine speed is more than 1500 RPM (2 trip detection logic), VTA is more than.63 volt and mass air flow meter output is less than 1.06 volts for 10 seconds or more. (Scheme 38)

Diagnostic Aids

Read freeze frame data using hand-held tester or OBD-II scan tool, as freeze frame data records engine conditions when a malfunction is detected. When troubleshooting, it is useful to determine whether vehicle was running or stopped, engine was warmed up or not, air-fuel ratio was lean or rich, etc. at time of malfunction.

Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If only DTC P0101 is displayed, replace mass air flow meter and retest system. If other codes are displayed, diagnose and repair those codes first and retest system.

For wiring diagram (Scheme 42) For diagnosis and repair (Scheme 43)- (Scheme 45).

Scheme 42

Scheme 43

Scheme 44

Scheme 45

For wiring diagram (Scheme 46) For diagnosis and repair (Scheme 47)- (Scheme 49).

Scheme 46

Scheme 47

Scheme 48

Scheme 49

For circuit description see Circuit Description under DTCs P0115, P0117 & P0118.

When THW is 95°F (35°C) or more and less than 140°F (60°C), and THA is 19.9°F (-6.7°C) or more when starting engine, and vehicle speed is changing, P0116 will set if THW change is lower than 37.4°F (3°C) from THW when starting engine (2 trip detection logic). DTC will also set if value of engine coolant temperature sensor will not change more than 33.8°F (1°C) even after repeating 6 trips (detection logic) of adjusting speed pattern with THW more than 140°F (60°C) when engine starts.

DTC P0125 will set if THW is less than 19.4°F (-7°C) for 20 minutes or more after starting engine, and engine coolant temperature sensor value is 68°F (20°C) or less (2 trip detection logic). DTC will also set if THW is 19.4°F (-7°C) or more and less than 50°F (10°C) 20 minutes or more after starting engine, and engine coolant temperature sensor value is 68°F (20°C) or less (2 trip detection logic). DTC will also set if THW is 50°F (10°C) or greater for 2 minutes or more after starting engine, and engine coolant temperature sensor value is 86°F (30°C) or less (2 trip detection logic).

For either DTC, check cooling system and engine coolant temperature sensor.

1. If different DTCs that are related to different systems are output simultaneously while terminal E2 is used as a ground terminal, terminal E2 may be open.
2. Read freeze frame data using hand-held tester or OBD-II scan tool, as freeze frame data records engine conditions when a malfunction is detected. When troubleshooting, it is useful to determine whether vehicle was running or stopped, engine was warmed up or not, air-fuel ratio was lean or rich, etc. at time of malfunction.

Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If other codes are displayed, diagnose and repair those codes first and retest system. If only DTCs P0116 or P0125 are displayed, check cooling system thermostat. Replace thermostat as necessary and retest system. If thermostat is okay, replace ECT sensor and retest system.

For wiring diagram (Scheme 50) For diagnosis and repair (Scheme 51)

Scheme 50

Scheme 51

If DTC is displayed, replace TP sensor.

1. Remove and inspect cooling system thermostat. If problem exists, replace thermostat as necessary and retest. If problem does not exist, go to next step.
2. If any other DTCs are displayed, diagnose and repair those DTCs first and retest. If only DTC P0128 is displayed, replace ECM.

For wiring diagram (Scheme 34) For diagnosis and repair (Scheme 52)- (Scheme 56).

Scheme 52

Scheme 53

Scheme 54

Scheme 55

Scheme 56

For wiring diagram (Scheme 36) For diagnosis and repair (Scheme 57)and (Scheme 58).

Scheme 57

Scheme 58

For wiring diagram (Scheme 34) For diagnosis and repair (Scheme 59)- (Scheme 63).

Scheme 59

Scheme 60

Scheme 61

Scheme 62

Scheme 63

For diagnosis and repair (Scheme 64)- (Scheme 68).

Scheme 64

Scheme 65

Scheme 66

Scheme 67

Scheme 68

For diagnosis and repair (Scheme 69)- (Scheme 72).

Scheme 69

Scheme 70

Scheme 71

Scheme 72

For wiring diagram (Scheme 73) For diagnosis and repair (Scheme 74)and (Scheme 75).

Scheme 73

Scheme 74

Scheme 75

For wiring diagram (Scheme 76) For diagnosis and repair (Scheme 77)and (Scheme 78).

Scheme 76

Scheme 77

Scheme 78

For wiring diagram (Scheme 76) For diagnosis and repair (Scheme 79)and (Scheme 80).

Scheme 79

Scheme 80

For wiring diagram (Scheme 76) For diagnosis and repair (Scheme 81)and (Scheme 82).

Scheme 81

Scheme 82

For wiring diagram (Scheme 83) For diagnosis and repair (Scheme 84)- (Scheme 86).

Scheme 83

Scheme 84

Scheme 85

Scheme 86

Read freeze frame data using hand-held tester or OBD-II scan tool, as freeze frame data records engine conditions when a malfunction is detected. When troubleshooting, it is useful to determine whether vehicle was running or stopped, engine was warmed up or not, air-fuel ratio was lean or rich, etc. at time of malfunction.

For diagnosis and repair (Scheme 87)

Scheme 87

For wiring diagram (Scheme 88) For diagnosis and repair (Scheme 89)- (Scheme 100).

Scheme 88

Scheme 89

Scheme 90

Scheme 91

Scheme 92

Scheme 93

Scheme 94

Scheme 95

Scheme 96

Scheme 97

Scheme 98

Scheme 99

Scheme 100

For wiring diagram (Scheme 88) For diagnosis and repair (Scheme 101)- (Scheme 106).

Scheme 101

Scheme 102

Scheme 103

Scheme 104

Scheme 105

Scheme 106

Confirmation Readiness Test

Note. Do not shut off engine or results will be invalid.

First Trip Procedure

1. Vehicle must be cold and ambient temperature must be 50-95°F (10-35°C).
2. Intake Air Temperature (IAT) and Engine Coolant Temperature (ECT) sensors have almost the same value.
3. Disconnect battery terminal or EFI and ETCS fuses to clear DTCs. Readiness tests will show INCMPL (incomplete).
4. Drive vehicle according to LA#4 driving cycle. Note the state of Readiness Tests. (Scheme 107) They will change to COMPL as EVAP evaluation monitors operate and if the system passes. This procedure may take approximately 20 minutes or more.

Scheme 107

Pass Condition - No Problem Found By ECM

1. If EVAP evaluation monitor shows COMPL, go to Non-Continuous Test Screen. (Scheme 108)
2. To get there, go to Advanced OBD-II, Onboard tests, Non-continuous Tests.
3. If all tests in time $02 category tests show Pass, EVAP evaluation monitor has operated and no problem was detected. (Scheme 109)

Scheme 108

Scheme 109

Fail Condition - Problem Detected By ECM

1. If EVAP evaluation monitor shows INCMPL, go to Non-Continuous Test Screen. (Scheme 110)
2. If all tests show Pass, EVAP evaluation monitor did not operate, EVAP evaluation monitor did not finish, or the ECM withheld judgement.
3. If one or more test in time $02 category shows Fail, EVAP evaluation monitor did operate and ECM detected a problem. (Scheme 111)
4. Go to Continuous Tests screen. This is the only place DTCs are listed for the first trip. (Scheme 112) The DTC listed may not be valid. A second trip is needed to confirm DTC.

Scheme 110

Scheme 111

Scheme 112

Second Trip Procedure

1. Vehicle must be cold and ambient temperature must be 50-95°F (10-35°C).
2. Go to Readiness Tests screen.
3. Drive vehicle according to LA#4 drive cycle. Note state of EVAP evaluation monitor. (Scheme 113) This procedure may take 20 minutes or more.
4. If Readiness Tests changes to COMPL, the EVAP evaluation monitor has operated. Check for any stored DTCs. If a DTC has stored, problem has been detected and confirmed by ECM. If no DTC was found, EVAP monitor operated but no problem was detected. (Scheme 112)

Scheme 113

1. If DTCs P0441 (purge flow), P0446 (VSV for CCV or VSV for pressure switching valve) P0451, P0452 or P0453 (evaporative pressure sensor) is output with DTCs P0442 or P0456, troubleshoot DTCs P0441, P0446, P0451, P0452 or P0453 first. If no malfunction is detected, troubleshoot DTCs P0442 or P0456 next.
2. Ask customer whether, after MIL came on, customer found fuel tank cap loose and tightened it. Also ask customer whether fuel tank cap was loose when refuelling. If fuel tank cap was loose, it was cause of DTC. If fuel tank cap was not loose or if customer was not sure if it was loose, troubleshoot according to diagnosis and repair. See appropriate Diagnosis & Repair.
3. Read freeze frame data using hand-held tester or OBD-II scan tool, as freeze frame data records engine conditions when a malfunction is detected. When troubleshooting, it is useful to determine whether vehicle was running or stopped, engine was warmed up or not, air-fuel ratio was lean or rich, etc. at time of malfunction. When ENGINE RUN TIME in freeze frame data is less than 200 seconds, carefully check vapor pressure sensor.

For wiring diagram (Scheme 88) For diagnosis and repair (Scheme 114)- (Scheme 119).

Scheme 114

Scheme 115

Scheme 116

Scheme 117

Scheme 118

Scheme 119

For diagnosis and repair, see Diagnosis & Repair (With OBD-II Scan Tool) under DTCs P0441 & P0446.

1. Inspect ECM (VC - 32). (Scheme 118), step 22. If not okay, check and replace ECM. If okay, go to step 2.
2. Inspect ECM (PTNK - 32). (Scheme 119), step 23. If okay, check and replace ECM. If not okay, go to step 3.
3. Check harness and connector (vapor pressure sensor - ECM). (Scheme 119), step 24. If not okay, repair or replace harness or connector. If okay, replace vapor pressure sensor assembly.

For wiring diagram (Scheme 120) For diagnosis and repair (Scheme 121)

Scheme 120

Scheme 121

Note. Brake switch may also be referred to as stoplight switch.

Signal of stoplight switch is used to judge whether acceleration system is abnormal or not. Stoplight switch has a duplex system (signals STP and ST1-) to memorize abnormality when signals of depressing and releasing brake pedal are detected simultaneously. For normal condition, see BRAKE SWITCH "A"/"B" NORMAL CONDITION table.

If DTC is set, ignition switch is on, brake pedal is released and STP signal is off when ST1- signal is off. Possible causes are short in stoplight switch signal circuit, faulty stoplight switch, and/or faulty ECM.

BRAKE SWITCH "A"/"B" NORMAL CONDITION

Read freeze frame data using hand-held tester or OBD-II scan tool, as freeze frame data records engine conditions when a malfunction is detected. When troubleshooting, it is useful to determine whether vehicle was running or stopped, engine was warmed up or not, air-fuel ratio was lean or rich, etc. at time of malfunction.

For wiring diagram (Scheme 122) For diagnosis and repair (Scheme 123)

Scheme 122

Scheme 123

For wiring diagram (Scheme 122) For diagnosis and repair (Scheme 124)and (Scheme 125).

Scheme 124

Scheme 125

For diagnosis and repair (Scheme 126)and (Scheme 127).

Scheme 126

Scheme 127

For wiring diagram (Scheme 128) For diagnosis and repair (Scheme 129)

Scheme 128

Scheme 129

For wiring diagram (Scheme 122) For diagnosis and repair with hand-held tester (Scheme 123) For diagnosis and repair with OBD-II scan tool (Scheme 124)and (Scheme 125).

Repair or replace ECM.

For wiring diagram (Scheme 130) For diagnosis and repair (Scheme 131)

Scheme 130

Scheme 131

For wiring diagram (Scheme 130) For diagnosis and repair (Scheme 132)

Scheme 132

For wiring diagram (Scheme 133)and (Scheme 134). For diagnosis and repair (Scheme 135)- (Scheme 137).

Scheme 133

Scheme 134

Scheme 135

Scheme 136

Scheme 137

For wiring diagram (Scheme 122) For diagnosis and repair (Scheme 138)

Scheme 138

For wiring diagram (Scheme 122) For diagnosis and repair (Scheme 139)

Scheme 139

For wiring diagram (Scheme 140) For diagnosis and repair (Scheme 141)and (Scheme 142).

Scheme 140

Scheme 141

Scheme 142

For wiring diagram (Scheme 140) For diagnosis and repair (Scheme 143)and (Scheme 144).

Scheme 143

Scheme 144

Throttle motor is operated by ECM and opens and closes throttle valve. Opening angle of throttle valve is detected by throttle position sensor which is mounted on throttle body. It provides feedback to ECM to control throttle motor to make throttle valve opening angle correct in response to driving condition. If malfunction is detected, ECM shuts down power for throttle motor, and throttle valve is fully closed by return spring. Throttle valve is locked at a certain opening angle. Also, entire electronically controlled throttle operation is cancelled until system returns to normal and ignition switch is turned off.

Possible causes are

1. Faulty throttle control motor circuit.
2. Faulty throttle control motor.
3. Faulty throttle body.
4. Faulty throttle valve.

Read freeze frame data using hand-held tester or OBD-II scan tool, as freeze frame data records engine conditions when a malfunction is detected. When troubleshooting, it is useful to determine whether vehicle was running or stopped, engine was warmed up or not, air-fuel ratio was lean or rich, etc. at time of malfunction.

For wiring diagram (Scheme 140) For diagnosis and repair (Scheme 145)

Scheme 145

For wiring diagram (Scheme 146) For diagnosis and repair (Scheme 147)

Scheme 146

Scheme 147

For wiring diagram (Scheme 140) For diagnosis and repair (Scheme 148)

Scheme 148

For wiring diagram (Scheme 149) For diagnosis and repair (Scheme 150)and (Scheme 151).

Scheme 149

Scheme 150

Scheme 151

For wiring diagram (Scheme 149) For diagnosis and repair (Scheme 152)and (Scheme 153).

Scheme 152

Scheme 153

For wiring diagram (Scheme 149) For diagnosis and repair (Scheme 154)

Scheme 154

Test Drive Confirmation

For confirmation driving pattern, see Confirmation Driving Pattern under DTCs P0134 & P0154.

For wiring diagram (Scheme 34) For diagnosis and repair (Scheme 155)- (Scheme 159).

Scheme 155

Scheme 156

Scheme 157

Scheme 158

Scheme 159

For wiring diagram (Scheme 34) For diagnosis and repair (Scheme 160)and (Scheme 161).

Scheme 160

Scheme 161

DTC P2A00: AIR/FUEL SENSOR CIRCUIT SLOW RESPONSE (BANK 1 SENSOR 1) & P2A03: AIR/FUEL SENSOR CIRCUIT SLOW RESPONSE (BANK 2 SENSOR 1)

Note. Bank No. 1 is also know as right bank (RH).

Note. For component location, see appropriate illustration in THEORY & OPERATION article.

For circuit description, see Circuit Description under DTCs P0031, P0032, P0051 & P0052. DTC is set when engine is warmed up, vehicle is driven at engine speed of 1400 RPM or more and vehicle speed is 38 MPH or more. In this condition, air/fuel ratio sensor output voltage change value is below regular value against fuel trim change value. ECM judges that air/fuel ratio sensor circuit has slow response. Possible causes are

1. A/F ratio sensor circuit is open or shorted.
2. Defective A/F ratio sensor.
3. Defective A/F sensor heater.
4. Defective A/F ratio sensor heater relay.
5. Defective A/F ratio sensor heater and relay circuit.
6. Faulty air induction system.
7. Faulty fuel pressure.
8. Faulty injector.
9. Defective ECM.

1. Using the hand-held tester only, it is possible to narrow down trouble area by performing ACTIVE TEST of "A/F CONTROL" (oxygen sensor or another can be distinguished). "A/F CONTROL" is an ACTIVE TEST which changes injection volume to -12.5 percent or +25 percent. Connect the hand-held tester to DLC3. see scheme 1 Turn ignition switch on. Warm up the engine with engine speed at 2500 RPM for approximately 90 seconds. Select item "DIAGNOSIS/ENHANCED OBD-II/ACTIVE TEST/AF CONTROL". Perform "A/F CONTROL" in idle condition (press right or left button). There is a few second delay in sensor 1 (front air/fuel ratio sensor) output. There is about a 20 second delay in sensor 2 (rear oxygen sensor). Air/fuel ratio sensor and oxygen sensor react synchronized with increase and decrease of injection volume (+25 percent to rich output: one volt, -12.5 percent to lean output: zero volts). see scheme 153
2. To display graph indication, select and push "YES or NO" button 2 data "AFS B1S1 and O2S B1S2" or "AFS B2S1 and O2S B2S2" and press button "4" after selecting "ACTIVE TEST/AF CONTROL/USER DATA".
3. DTCs P2A00 or P2A03 may also be detected when air/fuel ratio is stuck rich or lean.
4. Read freeze frame data using hand-held tester or OBD-II scan tool, as freeze frame data records engine conditions when a malfunction is detected. When troubleshooting, it is useful to determine whether vehicle was running or stopped, engine was warmed up or not, air-fuel ratio was lean or rich, etc. at time of malfunction.

For wiring diagram (Scheme 34) For diagnosis and repair (Scheme 162)- (Scheme 166).

Scheme 162

Scheme 163

Scheme 164

Scheme 165

Scheme 166