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) [08/2015 - ]: 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 and ECT / Trouble Codes.
5. Read the DTCs.

   Result

   Result	Proceed to
   DTC P0171, P0172, P0174 and/or P0175 are 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.

Result: 

B 

GO TO DTC CHART 

(Refer to DIAGNOSTIC TROUBLE CODE CHART [08/2015 - 08/2019] , or refer to DIAGNOSTIC TROUBLE CODE CHART [08/2019 - ] )

Result: 

A 

See step  2

1. Check the PCV hose connections.

   OK

   PCV hose is connected correctly and is not damaged.

Result: 

NG 

REPAIR OR REPLACE PCV HOSE 

(Refer to REMOVAL [08/2015 - ] )

Result: 

OK 

See step  3

1. Check the intake system for vacuum leaks (Refer to ON-VEHICLE INSPECTION [08/2015 - ] ).

   OK

   No leaks in intake system.

Result: 

NG 

REPAIR OR REPLACE INTAKE SYSTEM 

Result: 

OK 

See step  4

1. Connect the Techstream to the DLC3.
2. Start the engine.
3. Turn the Techstream on.
4. Warm up the engine and run the engine at an engine speed of 2500 rpm for approximately 90 seconds.
5. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume / AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2.
6. Perform the Control the Injection Volume operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).
7. Monitor the voltage outputs of the air fuel ratio sensor and the heated oxygen sensor (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 -12.5% to 12.5%. The injection volume can be changed in fine gradations.
   • 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

   Techstream Display (Sensor)	Injection Volume	Status	Voltage
   AFS Voltage B1S1 or AFS Voltage B2S1 (Air fuel ratio)	12.5%	Rich	Below 3.1 V
   	-12.5%	Lean	Higher than 3.4 V
   O2S B1S2 or O2S B2S2 (Heated oxygen)	12.5%	Rich	Higher than 0.55 V
   	-12.5%	Lean	Below 0.4 V

   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

   1. Lean: During Control the Injection Volume, the air fuel ratio sensor output voltage (AFS Voltage B1S1 or AFS Voltage B2S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S B1S2 or O2S B2S2) is consistently below 0.4 V.
   2. Rich: During Control the Injection Volume, the AFS Voltage B1S1 or AFS Voltage B2S1 is consistently below 3.1 V, and the O2S B1S2 or O2S B2S2 is consistently higher than 0.55 V.
   3. Lean/Rich: During Control the Injection Volume of the Active Test, the output voltage of the 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 [08/2015 - 08/2019] , or refer to DATA LIST / ACTIVE TEST [08/2019 - ] ).

Result: 

B 

See step  11

Result: 

A 

See step  5

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 and ECT / Data List / Coolant Temp.
5. Read the Data List twice, when the engine is both cold and warmed up.

   Standard

   With cold engine 

   Same as ambient air temperature.

   With warm engine 

   Between 75°C and 100°C (167°F and 212°F)

Result: 

NG 

REPLACE ENGINE COOLANT TEMPERATURE SENSOR 

(Refer to REMOVAL [08/2015 - ] )

Result: 

OK 

See step  6

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 and ECT / Data List / MAF and Coolant Temp.
5. Allow the engine to idle until Coolant Temp reaches 75°C (167°F) or higher.
6. Read MAF with the engine speed at 2500 rpm.

   Standard

   Between 8 gm/sec and 19 gm/sec (shift lever: N, A/C: Off).

Result: 

NG 

See step  16

Result: 

OK 

See step  7

1. Check the fuel pressure (Refer to PROCEDURE - Step 2 ).

Result: 

NG 

REPAIR OR REPLACE FUEL SYSTEM 

Result: 

OK 

See step  8

1. Check for exhaust gas leaks.

   OK

   No gas leaks.

Result: 

NG 

REPAIR OR REPLACE EXHAUST SYSTEM 

Result: 

OK 

See step  9

1. Perform a spark test (Refer to PROCEDURE - Step 1 ).

   HINT: 

   If the result of the spark test is normal, proceed to the next step.

Result: 

NEXT 

See step  10

1. Check the injection and volume (Refer to INSPECTION [08/2015 - ] ).

Result: 

OK 

See step  15

Result: 

NG 

REPLACE FUEL INJECTOR ASSEMBLY 

(Refer to REMOVAL [08/2015 - ] )

1. Inspect the air fuel ratio sensor (Refer to INSPECTION [08/2015 - ] ).

Result: 

NG 

REPLACE AIR FUEL RATIO SENSOR 

(Refer to REMOVAL [08/2015 - ] )

Result: 

OK 

See step  12

Refer to PROCEDURE - Step 2 [08/2015 - 08/2019] , or refer to PROCEDURE - Step 2 [08/2019 - ]

Result: 

NG 

See step  21

Result: 

OK 

See step  13

Refer to PROCEDURE - Step 3 [08/2015 - 08/2019] , or refer to PROCEDURE - Step 3 [08/2019 - ]

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR FUEL RATIO SENSOR - ECM) 

Result: 

OK 

See step  14

1. Replace the air fuel ratio sensor (Refer to REMOVAL [08/2015 - ] ).

Result: 

NEXT 

See step  15

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Clear the DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] , or refer to DTC CHECK / CLEAR [08/2019 - ] ).
5. Turn the ignition switch off.
6. Turn the ignition switch to ON and turn the Techstream on.
7. Start the engine and warm it up.
8. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.
9. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
10. Read the pending DTCs.

    Result

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

Result: 

B 

END 

Result: 

A 

See step  16

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 [08/2015 - ] ).

   HINT: 

   Repair any problems.

Result: 

NEXT 

See step  17

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Clear the DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] , or refer to DTC CHECK / CLEAR [08/2019 - ] ).
5. Turn the ignition switch off.
6. Turn the ignition switch to ON and turn the Techstream on.
7. Start the engine and warm it up.
8. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
9. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
10. Read the pending DTCs.
    RESULT
    
    

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

Result: 

B 

END 

Result: 

A 

See step  18

Refer to PROCEDURE - Step 3 [08/2015 - 08/2019] , or refer to PROCEDURE - Step 7 [08/2019 - ]

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  19

1. Replace the mass air flow meter (Refer to REMOVAL [08/2015 - ] ).

   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.

Result: 

NEXT 

See step  20

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Clear the DTCs (Refer to DTC CHECK / CLEAR [08/2015 - 08/2019] , or refer to DTC CHECK / CLEAR [08/2019 - ] ).
5. Turn the ignition switch off.
6. Turn the ignition switch to ON and turn the Techstream on.
7. Start the engine and warm it up.
8. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
9. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
10. Read the pending DTCs.
    RESULT
    
    

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

Result: 

A 

END 

Result: 

B 

REPLACE ECM 

(Refer to REMOVAL [08/2015 - ] )

Refer to PROCEDURE - Step 5 [08/2015 - 08/2019] , or refer to PROCEDURE - Step 5 [08/2019 - ]

Result: 

NG 

REPLACE NO. 1 INTEGRATION RELAY 

Result: 

OK 

See step  22

Refer to PROCEDURE - Step 6 [08/2015 - 08/2019] , or refer to PROCEDURE - Step 6 [08/2019 - ]

Result: 

OK 

CHECK ECM POWER SOURCE CIRCUIT 

(Refer to ECM Power Source Circuit [08/2015 - 08/2019] , or refer to ECM Power Source Circuit [08/2019 - 08/2022] , or refer to ECM Power Source Circuit [08/2022 - ] )

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (NO. 1 INTEGRATION RELAY - A/F SENSOR AND BODY GROUND)