DTC P0171: System Too Lean (Bank 1); DTC P0172: System Too Rich (Bank 1); DTC P0174: System Too Lean (Bank 2); DTC P0175: System Too Rich (Bank 2) [08/2013 - ]: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine / Trouble Codes.
5. Read DTCs.
   RESULT
   
   

   Result	Proceed to
   DTC P0171, P0172, P0174 or P0175 is output	A
   DTC P0171, P0172, P0174 or P0175 and other DTCs are output	B

   HINT: 

   If any DTCs other than P0171, P0172, P0174 or P0175 are output, troubleshoot those DTCs first.

B → See step   23 

A: Go to next step 

1. Check the PCV hose connections. Refer to COMPONENTS [08/2013 - ] .

   OK

   PCV valve and hose are connected correctly and are not damaged.

NG → REPAIR OR REPLACE PCV HOSE 

OK: Go to next step 

1. Check the intake system for vacuum leaks.

   OK

   No leaks from intake system.

NG → REPAIR OR REPLACE INTAKE SYSTEM 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Start the engine.
3. Turn the Techstream on.
4. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
5. Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume.
6. Perform the Control the Injection Volume operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
7. Monitor the voltage outputs of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2) displayed on the Techstream.

   HINT: 

   • Change the fuel injection volume within the range of -12% to +12%. The injection volume can be changed in fine gradations within this range.
   • Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
   • The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.
   • If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

   Standard Voltage

   Techstream Display (Sensor)	Injection Volume	Status	Voltage
   AFS Voltage B1S1 or AFS Voltage B2S1 (Air fuel ratio)	+12%	Rich	Less than 3.1
   	-12%	Lean	More than 3.4
   O2S B1S2 or O2S B2S2 (Heated oxygen)	+12%	Rich	More than 0.55
   	-12%	Lean	Less than 0.4

   RESULT
   
   

   Status AFS Voltage B1S1 or AFS Voltage B2S1	Status O2S B1S2 or O2S B2S2	Air Fuel Ratio Condition and Air Fuel Ratio Sensor Condition	Suspected Trouble Area	Proceed to
   Lean/Rich	Lean/Rich	Normal	-	A
   Lean	Lean	Actual air fuel ratio lean	PCV valve and hose PCV hose connections Fuel injector assembly blockage Gas leak from exhaust system Intake system Fuel pressure Mass air flow meter Engine coolant temperature sensor	A
   Rich	Rich	Actual air fuel ratio rich	Fuel injector assembly leak or blockage Gas leak from exhaust system Ignition system Fuel pressure Mass air flow meter Engine coolant temperature sensor	A
   Lean	Lean/Rich	Air fuel ratio sensor malfunction	Air fuel ratio sensor	B
   Rich	Lean/Rich	Air fuel ratio sensor malfunction	Air fuel ratio sensor	B

   Lean: During Control the Injection Volume, the air fuel ratio sensor output voltage (AFS Voltage B1S1 or AFS Voltage B2S1) is consistently more than 3.4 V, and the heated oxygen sensor output voltage (O2S B1S2 or O2S B2S2) is consistently less than 0.4 V.

   Rich: During Control the Injection Volume, the AFS Voltage B1S1 or AFS Voltage B2S1 is consistently less than 3.1 V, and the O2S B1S2 or O2S B2S2 is consistently more than 0.55 V.

   Lean/Rich: During Control the Injection Volume of the Active Test, the output voltage of the air fuel ratio sensor and heated oxygen sensor alternates correctly.

   HINT: 

   Refer to "Data List / Active Test" [AFS Voltage B1S1, AFS Voltage B2S1, O2S B1S2 and O2S B2S2]. Refer to DATA LIST / ACTIVE TEST [08/2013 - ] .

B → See step   11 

A: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine / Data List / Coolant Temp.
5. Read the Coolant Temp twice, when the engine is both cold and warmed up.

   Standard

   Techstream Display	Condition	Specified Condition
   Coolant Temp	Cold engine	Same as ambient air temperature
   	Warm engine	Between 75 and 100°C (167 and 212°F)

NG → See step   24 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine / Data List / MAF, Coolant Temp and Engine Speed.
5. Read MAF with the engine speed at 3000 rpm.

   Standard

   Techstream Display	Condition	Specified Condition
   MAF	Shift lever position: N (Neutral) A/C: Off Engine Speed: 3000 rpm	Between 11 gm/sec. and 16 gm/sec

NG → See step   16 

OK: Go to next step 

1. Check the fuel pressure. Refer to ON-VEHICLE INSPECTION [08/2013 - ] - Step 2 .

NG → REPAIR OR REPLACE FUEL SYSTEM 

OK: Go to next step 

1. Check for exhaust gas leaks.

   OK

   No exhaust gas leaks.

NG → REPAIR OR REPLACE EXHAUST GAS LEAK POINT 

OK: Go to next step 

1. Perform a spark test.

   HINT: 

   • Refer to the ignition system inspection procedure. Refer to ON-VEHICLE INSPECTION [08/2013 - ] .
   • If the spark plugs or ignition system malfunctions, engine misfire may occur. The misfire count can be read using the Techstream. Enter the following menus: Powertrain / Engine / Data List / Cylinder #1 Misfire Count (to Cylinder #6 Misfire Count).

NG → REPAIR OR REPLACE IGNITION SYSTEM 

OK: Go to next step 

1. Check the injection and volume.

   HINT: 

   • Refer to the fuel injector assembly inspection procedure. Refer to INSPECTION [08/2013 - ] - Step 1 .
   • If the injectors malfunction, engine misfire may occur. The misfire count can be read using the Techstream. Enter the following menus: Powertrain / Engine / Data List / Cylinder #1 Misfire Count (to Cylinder #6 Misfire Count).

OK → See step   15 

NG → See step   25 

1. Inspect the air fuel ratio sensor. Refer to INSPECTION [08/2013 - ] - Step 1 .

NG → See step   26 

OK: Go to next step 

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the air fuel ratio sensor connector.
2. Turn the ignition switch to ON.
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   B14-2 (+B) - Body ground	Ignition switch ON	11 to 14 V
   B13-2 (+B) - Body ground	Ignition switch ON	11 to 14 V

   TEXT IN ILLUSTRATION
   
   

   *a	Front view of wire harness connector (to Air Fuel Ratio Sensor)
   *b	for Bank 1
   *c	for Bank 2

NG → See step   21 

OK: Go to next step 

1. Disconnect the air fuel ratio sensor connector.
2. Disconnect the ECM connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   B14-1 (HA1A) - B1-22 (HA1A)	Always	Below 1 Ω
   B14-3 (A1A+) - B1-126 (A1A+)	Always	Below 1 Ω
   B14-4 (A1A-) - B1-125 (A1A-)	Always	Below 1 Ω
   B13-1 (HA2A) - B1-20 (HA2A)	Always	Below 1 Ω
   B13-3 (A2A+) - B1-103 (A2A+)	Always	Below 1 Ω
   B13-4 (A2A-) - B1-102 (A2A-)	Always	Below 1 Ω
   B14-1 (HA1A) or B1-22 (HA1A) - Body ground	Always	10 kΩ or higher
   B14-3 (A1A+) or B1-126 (A1A+) - Body ground	Always	10 kΩ or higher
   B14-4 (A1A-) or B1-125 (A1A-) - Body ground	Always	10 kΩ or higher
   B13-1 (HA2A) or B1-20 (HA2A) - Body ground	Always	10 kΩ or higher
   B13-3 (A2A+) or B1-103 (A2A+) - Body ground	Always	10 kΩ or higher
   B13-4 (A2A-) or B1-102 (A2A-) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Replace the air fuel ratio sensor. Refer to REMOVAL [08/2013 - ] .

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Clear DTCs. Refer to DTC CHECK / CLEAR [08/2013 - ] .
5. Turn the ignition switch off and wait for at least 30 seconds.
6. Turn the ignition switch to ON.
7. Turn the Techstream on.
8. Start the engine and warm it up.
9. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.
10. Enter the following menus: Powertrain / Engine / Trouble Codes.
11. Read the pending DTCs.
    RESULT
    
    

    Result	Proceed to
    DTC P0171, P0172, P0174 or P0175 is output	A
    DTC is not output	B

B → END 

A: Go to next step 

1. Check the connection and terminal contact pressure of connectors and wire harnesses between the mass air flow meter and ECM. Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE [08/2013 - ] .

   HINT: 

   Repair any problems.

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Clear DTCs. Refer to DTC CHECK / CLEAR [08/2013 - ] .
5. Turn the ignition switch off and wait for at least 30 seconds.
6. Turn the ignition switch to ON.
7. Turn the Techstream on.
8. Start the engine and warm it up.
9. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.
10. Enter the following menus: Powertrain / Engine / Trouble Codes.
11. Read the pending DTCs.
    RESULT
    
    

    Result	Proceed to
    DTC P0171, P0172, P0174 or P0175 is output	A
    DTC is not output	B

B → END 

A: Go to next step 

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Replace the mass air flow meter. Refer to REMOVAL [08/2013 - ] .

   HINT: 

   If the result of the inspection performed in step 6 indicated no problem, proceed to the next step without replacing the mass air flow meter.

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Clear DTCs. Refer to DTC CHECK / CLEAR [08/2013 - ] .
5. Turn the ignition switch off and wait for at least 30 seconds.
6. Turn the ignition switch to ON.
7. Turn the Techstream on.
8. Start the engine and warm it up.
9. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.
10. Enter the following menus: Powertrain / Engine / Trouble Codes.
11. Read the pending DTCs.
    RESULT
    
    

    Result	Proceed to
    DTC is not output	A
    DTC P0171, P0172, P0174 or P0175 is output	B

B → See step   28 

A → END 

1. Disconnect the air fuel ratio sensor connector.
2. Remove the A/F HTR relay from the engine room relay block.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   B14-2 (+B) - 3 (A/F HTR relay holder)	Always	Below 1 Ω
   B13-2 (+B) - 3 (A/F HTR relay holder)	Always	Below 1 Ω
   B14-2 (+B) or 3 (A/F HTR relay holder) - Body ground	Always	10 kΩ or higher
   B13-2 (+B) or 3 (A/F HTR relay holder) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Remove the A/F HTR relay from the engine room relay block.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   3 - 5	Battery voltage not applied	10 kΩ or higher
   	Battery voltage applied to terminals 1 and 2	Below 1 Ω

NG → REPLACE A/F HTR RELAY 

OK → See step   27