DTC P0171: System Too Lean (Bank 1); DTC P0172: System Too Rich (Bank 1) [10/2014 - ]: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
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 or P0172 is output	A
   DTC P0171 or P0172 and other DTCs are output	B

   HINT: 

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

Result: 

B 

GO TO DTC CHART 

(Refer to DIAGNOSTIC TROUBLE CODE CHART [10/2014 - 10/2015] or DIAGNOSTIC TROUBLE CODE CHART [10/2015 - 10/2016] or DIAGNOSTIC TROUBLE CODE CHART [10/2016 - 06/2017] or DIAGNOSTIC TROUBLE CODE CHART [06/2017 - ] )

Result: 

A 

See step  2

1. Check the PCV hose connections (Refer to COMPONENTS [10/2014 - ] ).

   OK

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

Result: 

NG 

REPAIR OR REPLACE PCV HOSE 

Result: 

OK 

See step  3

1. Check the intake system for vacuum leaks (Refer to ON-VEHICLE INSPECTION [10/2014 - ] ).

   OK

   No leaks in intake system.

   HINT: 

   Perform "Inspection After Repair" after repairing or replacing the intake system (Refer to INITIALIZATION [10/2014 - ] ).

Result: 

NG 

REPAIR OR REPLACE INTAKE SYSTEM 

Result: 

OK 

See step  4

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Put the engine in inspection mode (maintenance mode) (Refer to INSPECTION MODE PROCEDURE [10/2014 - ] ).
5. Start the engine.
6. Warm up the engine and run the engine at an engine speed of 2500 rpm for approximately 90 seconds.

   HINT: 

   During charge control, the engine speed is set at idle. Therefore, the engine speed does not increase when depressing the accelerator pedal. In this case, warm up the engine after charge control has completed.

7. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / Gas AF Control / AFS Voltage B1S1 and O2S B1S2.
8. Perform the Control the Injection Volume for A/F Sensor operation with the engine idling (press the 12.5% or -12.5% button to change the fuel injection volume).
9. Monitor the voltage outputs of the air fuel ratio sensor and the heated oxygen sensor (AFS Voltage B1S1 and O2S B1S2) displayed on the Techstream.

   HINT: 

   • The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.
   • 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 (Air fuel ratio)	12.5%	Rich	Below 3.1 V
   	-12.5%	Lean	Higher than 3.4 V
   O2S B1S2 (Heated oxygen)	12.5%	Rich	Higher than 0.55 V
   	-12.5%	Lean	Below 0.4 V

   RESULT
   
   

   Status AFS Voltage B1S1	Status O2S B1S2	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 sub-assembly Engine coolant temperature sensor EGR valve assembly	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 sub-assembly Engine coolant temperature sensor	A
   Lean	Lean/Rich	Air fuel ratio sensor malfunction	Air fuel ratio sensor EGR valve assembly	B
   Rich	Lean/Rich	Air fuel ratio sensor malfunction	Air fuel ratio sensor	B

   • Lean: During Control the Injection Volume for A/F Sensor Active Test, the air fuel ratio sensor output voltage (AFS Voltage B1S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S B1S2) is consistently below 0.4 V.
   • Rich: During Control the Injection Volume for A/F Sensor Active Test, the AFS Voltage B1S1 is consistently below 3.1 V, and the O2S B1S2 is consistently higher than 0.55 V.
   • Lean/Rich: During Control the Injection Volume for A/F Sensor Active Test, the output voltage of the air fuel ratio sensor or heated oxygen sensor alternates correctly.

   HINT: 

   Refer to "Data List / Active Test" [AFS Voltage B1S1 and O2S B1S2] (Refer to DATA LIST / ACTIVE TEST [10/2014 - 10/2015] or DATA LIST / ACTIVE TEST [10/2015 - ] ).

Result: 

B 

See step  11

Result: 

A 

See step  5

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / Coolant Temp.
5. Read the Data List 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)

   HINT: 

   Perform "Inspection After Repair" after replacing the engine coolant temperature sensor (Refer to INITIALIZATION [10/2014 - ] ).

Result: 

NG 

REPLACE ENGINE COOLANT TEMPERATURE SENSOR 

(Refer to REMOVAL [10/2014 - ] )

Result: 

OK 

See step  6

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Put the engine in inspection mode (maintenance mode) (Refer to INSPECTION MODE PROCEDURE [10/2014 - ] ).
5. Start the engine.
6. Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / MAF, Coolant Temp and Engine Speed.
7. Allow the engine to idle until Coolant Temp reaches 75°C (167°F) or higher.
8. Read MAF with the engine speed at 2500 rpm.

   HINT: 

   During charge control, the engine speed is set at idle. Therefore, the engine speed does not increase when depressing the accelerator pedal. In this case, read the Data List after charge control has completed.

   Standard

   Techstream Display	Condition	Specified Condition
   MAF	Shift lever position: N A/C: Off Engine Speed: 2500 rpm	Between 5.0 and 9.0 gm/s

Result: 

NG 

See step  18

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.

   HINT: 

   Perform "Inspection After Repair" after repairing or replacing the exhaust system (Refer to INITIALIZATION [10/2014 - ] ).

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.
   • 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 and ECT / Data List / Gas Misfire / Cylinder #1 Misfire Count (to Cylinder #4 Misfire Count).
   • Perform "Inspection After Repair" after repairing or replacing the ignition system (Refer to INITIALIZATION [10/2014 - ] ).

Result: 

NEXT 

See step  10

1. Check the injection and volume.

   HINT: 

   • Refer to the fuel injector assembly inspection procedure (Refer to INSPECTION [10/2014 - ] ).
   • If the fuel injector assembly malfunction, engine misfire may occur. The misfire count can be read using the Techstream. Enter the following menus: Powertrain / Engine and ECT / Data List / Gas Misfire / Cylinder #1 Misfire Count (to Cylinder #4 Misfire Count).
   • Perform "Inspection After Repair" after replacing the fuel injector assembly (Refer to INITIALIZATION [10/2014 - ] ).

Result: 

OK 

See step  15

Result: 

NG 

REPLACE FUEL INJECTOR ASSEMBLY 

(Refer to REMOVAL [10/2014 - ] )

See step  1Refer to PROCEDURE - Step 1

Result: 

NG 

REPLACE AIR FUEL RATIO SENSOR 

(Refer to REMOVAL [10/2014 - ] )

Result: 

OK 

See step  12

See step  2Refer to PROCEDURE - Step 2

Result: 

NG 

See step  23

Result: 

OK 

See step  13

Refer to PROCEDURE - Step 1

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  14

1. Replace the air fuel ratio sensor (Refer to REMOVAL [10/2014 - ] ).

   HINT: 

   Perform "Inspection After Repair" after replacing the air fuel ratio sensor (Refer to INITIALIZATION [10/2014 - ] ).

Result: 

NEXT 

See step  15

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Clear the DTCs (Refer to DTC CHECK / CLEAR [10/2014 - ] ).
5. Turn the power switch off and wait for at least 30 seconds.
6. Turn the power switch on (IG).
7. Turn the Techstream on.
8. Put the engine in inspection mode (maintenance mode) (Refer to INSPECTION MODE PROCEDURE [10/2014 - ] ).
9. Start the engine and warm it up.
10. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
11. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
12. Read the DTCs.
    RESULT
    
    

    Result	Proceed to
    DTC P0171 or P0172 is output	A
    DTCs are not output	B

Result: 

B 

END 

Result: 

A 

See step  16

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Put the engine in inspection mode (maintenance mode) (Refer to INSPECTION MODE PROCEDURE [10/2014 - ] ).
5. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

   HINT: 

   The A/C switch and all accessory switches should be off.

6. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position / Data List / Primary / MAP and Throttle Idle Position.
7. Confirm that the Throttle Idle Position is ON and check the MAP value in the Data List while performing the Active Test.

   HINT: 

   • Do not leave the EGR valve open for 10 seconds or more during the Active Test.
   • Be sure to return the EGR valve to step 0 when the Active Test is completed.
   • Do not open the EGR valve 30 steps or more during the Active Test.

   OK

   MAP change in response to EGR step position when Throttle Idle Position is ON in Data List.

   Standard

   -	EGR Step Position (Active Test)
   	0 Steps	0 to 30 Steps
   MAP (Data List)	(EGR valve is fully closed)	MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed

   HINT: 

   • While performing the Active Test, if the increase in the value of MAP is small, the EGR valve assembly may be a malfunctioning.
   • Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of MAP may occur while performing the Active Test. However, the amount that the value of MAP increases will be smaller than normal.
   RESULT
   
   

   Result	Proceed to
   NG	A
   OK	B

Result: 

B 

See step  18

Result: 

A 

See step  17

1. Remove the EGR valve assembly (Refer to REMOVAL [10/2014 - ] ).
2. Check if the EGR valve is stuck open.

   OK

   EGR valve is tightly closed.

   HINT: 

   Perform "Inspection After Repair" after replacing the EGR valve assembly (Refer to INITIALIZATION [10/2014 - ] ).

Result: 

NG 

REPLACE EGR VALVE ASSEMBLY 

(Refer to REMOVAL [10/2014 - ] )

Result: 

OK 

See step  18

1. Check the connection and terminal contact pressure of connectors and wire harnesses between the mass air flow meter sub-assembly and ECM (Refer to ELECTRONIC CIRCUIT INSPECTION PROCEDURE [10/2014 - ] ).

   HINT: 

   Repair any problems.

Result: 

NEXT 

See step  19

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Clear the DTCs (Refer to DTC CHECK / CLEAR [10/2014 - ] ).
5. Turn the power switch off and wait for at least 30 seconds.
6. Turn the power switch on (IG).
7. Turn the Techstream on.
8. Put the engine in inspection mode (maintenance mode) (Refer to INSPECTION MODE PROCEDURE [10/2014 - ] ).
9. Start the engine and warm it up.
10. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
11. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
12. Read the DTCs.
    RESULT
    
    

    Result	Proceed to
    DTC P0171 or P0172 is output	A
    DTCs are not output	B

Result: 

B 

END 

Result: 

A 

See step  20

See step  3

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  21

1. Replace the mass air flow meter sub-assembly (Refer to REMOVAL [10/2014 - ] ).

   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 sub-assembly.
   • Perform "Inspection After Repair" after replacing the mass air flow meter sub-assembly (Refer to INITIALIZATION [10/2014 - ] ).

Result: 

NEXT 

See step  22

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Clear the DTCs (Refer to DTC CHECK / CLEAR [10/2014 - ] ).
5. Turn the power off and wait for at least 30 seconds.
6. Turn the power switch on (IG).
7. Turn the Techstream on.
8. Put the engine in inspection mode (maintenance mode) (Refer to INSPECTION MODE PROCEDURE [10/2014 - ] ).
9. Start the engine and warm it up.
10. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
11. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
12. Read the DTCs.
    RESULT
    
    

    Result	Proceed to
    DTCs are not output	A
    DTC P0171 or P0172 is output	B

Result: 

A 

END 

Result: 

B 

REPLACE ECM 

(Refer to REMOVAL [10/2014 - ] )

See step  5Refer to PROCEDURE - Step 5

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  24

See step  6Refer to PROCEDURE - Step 6

Result: 

OK 

REPLACE NO. 1 INTEGRATION RELAY 

(Refer to REMOVAL [10/2014 - ] )

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - NO. 1 INTEGRATION RELAY)