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): Wiring Diagram
Refer to DTC P2195 .
HINT:
Intelligent tester only:
Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE TEST. The A/F CONTROL function can help to determine whether the Air-Fuel Ratio (A/F) sensor, Heated Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.
The following instructions describe how to conduct the A/F CONTROL operation using an intelligent tester.
- Connect the intelligent tester to the DLC3.
- Start the engine and turn the tester on.
- Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
- On the tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
- Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume.)
- Monitor the output voltages of the A/F and HO2 sensors (AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2) displayed on the tester.
HINT:
- The A/F CONTROL operation lowers the fuel injection volume by 12.5 % or increases the injection volume by 25 %.
- Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
| Tester Display (Sensor) | Injection Volume | Status | Voltage |
|---|---|---|---|
| AFS B1S1 or AFS B2S1 (A/F) | +25 % | Rich | Less than 3.0 V |
| AFS B1S1 or AFS B2S1 (A/F) | -12.5 % | Lean | More than 3.35 V |
| O2S B1S2 or O2S B2S2 (HO2) | +25 % | Rich | More than 0.55 V |
| O2S B1S2 or O2S B2S2 (HO2) | -12.5 % | Lean | Less than 0.4 V |
| Case | A/F Sensor (Sensor 1) Output Voltage | HO2 Sensor (Sensor 2) Output Voltage | Main Suspected Trouble Area | ||
|---|---|---|---|---|---|
| 1 | Injection Volume +25 % -12.5 % |
Injection Volume +25 % -12.5 % |
- | ||
| Output Voltage More than 3.35 V Less than 3.0 V |
Output Voltage More than 0.55 V Less than 0.4 V |
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| 2 | Injection Volume +25 % -12.5 % |
Injection Volume +25 % -12.5 |
|
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| Output Voltage Almost no reaction |
Output Voltage More than 0.55 V Less than 0.4 V |
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| 3 | Injection Volume +25 % -12.5 % |
Injection Volume +25 % -12.5 % |
|
||
| Output Voltage More than 3.35 V Less than 3.0 V |
Output Voltage Almost no reaction |
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| 4 | Injection volume +25 % -12.5 % |
Injection Volume +25 % -12.5 % |
|
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| Output Voltage Almost no reaction |
Output Voltage Almost no reaction |
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- Following the A/F CONTROL procedure enables technicians to check and graph the voltage outputs of both the A/F and HO2 sensors.
- To display the graph, enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL / USER DATA / AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2, and press the YES button and then the ENTER button followed by the F4 button.
HINT:
- Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction (See FREEZE FRAME DATA ).
- A low A/F sensor voltage could be caused by a rich air-fuel mixture. Check for conditions that would cause the engine to run rich.
- A high A/F sensor voltage could be caused by a rich air-fuel mixture. Check for conditions that would cause the engine to run lean.
- CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0171, P0172, P0174 OR P0175)
- Connect the intelligent tester to the DLC3.
- Turn the engine switch on (IG) and turn the tester on.
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
- Read DTCs.
Result
RESULT REFERENCEDisplay (DTC output) Proceed to P0171, P0172, P0174 or P0175 A P0171, P0172, P0174 or P0175 and other DTCs B HINT:
If any DTCs other than P0171, P0172, P0174 or P0175 are output, troubleshoot those DTCs first.
B : GO TO DTC CHART
A : GO TO NEXT STEP
- PERFORM SYSTEM CHECK (D-4S TEST)
- Connect the intelligent tester to the DLC3.
- Start the engine and turn the intelligent tester on.
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / SYSTEM CHECK / D-4S TEST / D-4S INJ SWITCH / PORT.
- Read the value SHORT FT #1 and LONG FT #1 and/or SHORT FT #2 and LONG FT #2.
OK: SHORT FT #1(#2) + LONG FT #1(#2) = Between - 19% and +19%
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / SYSTEM CHECK / D-4S TEST / D-4S INJ SWITCH / DIRECT.
- Read the value SHORT FT #1 and LONG FT #1 and/or SHORT FT #2 and LONG FT #2.
OK: SHORT FT #1(#2) + LONG FT #1(#2) = Between - 19% and +19%
Result
RESULT REFERENCEItem Proceed to PORT DIRECT OK OK A OK NG B NG OK C NG NG D
B : Go to step 20
C : Go to step 24
D : Go to step 5
A : GO TO NEXT STEP
- CHECK IF VEHICLE HAS RUN OUT OF FUEL IN PAST
YES : DTC CAUSED BY RUNNING OUT OF FUEL
NO : GO TO NEXT STEP
- CHECK FUEL PUMP RELAY
- Remove the F/PMP relay from the engine room J/B and R/B No. 2.
- Measure the resistance according to the value(s) in the table below.
Standard resistance
TESTER CONNECTION SPECIFIED CONDITIONTester Connection Specified Condition 3 - 4 10 kΩ or higher 3 - 4 Below 1 Ω (when battery voltage applied to terminals 1 and 2)
NG : REPLACE RELAY
OK : CHECK FOR INTERMITTENT PROBLEMS
- CHECK PCV HOSE
OK: PCV hose is connected correctly and is not damaged.
NG : REPAIR OR REPLACE PCV HOSE
OK : go to next step
- CHECK AIR INDUCTION SYSTEM
- Check the air induction system for vacuum leakage.
OK: No leakage from air induction system.
NG : REPAIR OR REPLACE AIR INDUCTION SYSTEM
OK : GO TO NEXT STEP
- Check the air induction system for vacuum leakage.
- PERFORM ACTIVE TEST BY INTELLIGENT TESTER (A/F CONTROL)
- Connect the intelligent tester to the DLC3.
- Start the engine and turn the tester on.
- Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
- On the tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
- Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
- Monitor the output voltages of the A/F and HO2 sensors (AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2) displayed on the tester.
HINT:
- The A/F CONTROL operation lowers the fuel injection volume by 12.5 % or increases the injection volume by 25 %.
- Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
INJECTION VOLUME STATUSTester Display (Sensor) Injection Volume Status Voltage AFS B1S1 or AFS B2S1 (A/F) +25 % Rich Less than 3.0 V AFS B1S1 or AFS B2S1 (A/F) -12.5 % Lean More than 3.35 V O2S B1S2 or O2S B2S2 (HO2) +25 % Rich More than 0.55 V O2S B1S2 or O2S B2S2 (HO2) -12.5 % Lean Less than 0.4 V Result
RESULT REFERENCEStatus AFS B1S1 or AFS B2S1 Status O2S B1S2 or O2S B2S2 A/F Condition and A/F Sensor Condition Misfire Suspected Trouble Area Proceed to Lean/Rich Lean/Rich Normal - - A Lean Lean Actual air-fuel ratio lean May occur - PCV valve and hose
- PCV hose connections
- Injector for port injection
- Gas leakage from exhaust system
- Air induction system
- Fuel pressure
- Mass Air Flow (MAF) meter
- Engine Coolant Temperature (ECT) sensor
A Rich Rich Actual air-fuel ratio rich - - Gas leakage from exhaust system
- Ignition system
- Fuel pressure
- MAF meter
- ECT sensor
A Lean Lean/Rich A/F sensor malfunction - - A/F sensor
B Rich Lean/Rich A/F sensor malfunction - - A/F sensor
B Lean:
During A/F CONTROL, the A/F sensor output voltage (AFS) is consistently more than 3.35 V, and the HO2 sensor output voltage (O2S) is consistently less than 0.4 V.
Rich:
During A/F CONTROL, the AFS is consistently less than 3.0 V, and the O2S is consistently more than 0.55 V.
B : Go to step 11
A : GO TO NEXT STEP
- READ VALUE OF INTELLIGENT TESTER (COOLANT TEMP)
- Connect the intelligent tester to the DLC3.
- Turn the engine switch on (IG) and turn the tester on.
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / COOLANT TEMP.
- Read the COOLANT TEMP twice, when the engine is both cold and warmed up.
Standard: With cold engine: Same as ambient air temperature.
With warm engine: Between 75 and 95°C (167 and 203°F)
NG : REPLACE ENGINE COOLANT TEMPERATURE SENSOR
OK : GO TO NEXT STEP
- READ VALUE OF INTELLIGENT TESTER (MAF)
- Connect the intelligent tester to the DLC3.
- Turn the engine switch on (IG) and turn the tester on.
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / MAF and COOLANT TEMP.
- Allow the engine to idle until the COOLANT TEMP reaches 75°C (167°F) or more.
- Read the MAF with the engine in an idling condition and at an engine speed of 2,500 rpm.
Standard:
- MAF while engine idling: Between 2.1 g/sec and 3.1 g/sec (shift position: N, A/C: OFF).
- MAF at an engine speed of 2,500 rpm: Between 7.8 g/sec and 11.4 g/sec (shift position: N, A/C: OFF).
NG : REPLACE MASS AIR FLOW METER
OK : GO TO NEXT STEP
- CHECK FOR EXHAUST GAS LEAKAGE
OK: No gas leakage.
NG : REPAIR OR REPLACE EXHAUST SYSTEM
OK : GO TO NEXT STEP
- INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
- Disconnect the E42 or E38 A/F sensor connector.
- Measure the resistance according to the value(s) in the table below.
Standard resistance (Bank 1 sensor 1)
TESTER CONNECTION SPECIFIED CONDITIONTester Connection Condition Specified Condition HA1A (1) - +B (2) 20°C (68°F) 1.8 Ω to 3.4 Ω HA1A (1) - A1A- (4) - 10 kΩ or higher Standard resistance (Bank 2 sensor 1)
TESTER CONNECTION SPECIFIED CONDITIONTester Connection Condition Specified Condition HA2A (1) - +B (2) 20°C (68°F) 1.8 Ω to 3.4 Ω HA2A (1) - A2A- (4) - 10 kΩ or higher - Reconnect the A/F sensor connector.
NG : REPLACE AIR FUEL RATIO SENSOR
OK : GO TO NEXT STEP
- INSPECT A/F HTR RELAY
- Remove the A/F HTR relay from the engine room J/B and R/B No. 2.
- Measure the resistance according to the value(s) in the table below.
Standard resistance
TESTER CONNECTION SPECIFIED CONDITIONTester Connection Specified Condition 3 - 5 10 kΩ or higher 3 - 5 Below 1 Ω (when battery voltage applied to terminals 1 and 2) - Reinstall the A/F HTR relay.
NG : REPLACE A/F HTR RELAY
OK : GO TO NEXT STEP
- CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)
- Disconnect the E42 and E38 A/F sensor connectors.
- Turn the engine switch on (IG).
- Measure the voltage according to the value(s) in the table below.
Standard voltage
TESTER CONNECTION SPECIFIED CONDITIONTester Connection Specified Condition +B (E42-2) - Body ground 9 to 14 V +B (E38-2) - Body ground 9 to 14 V - Turn the engine switch off.
- Disconnect the E6 ECM connector.
- Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open)
TESTER CONNECTION SPECIFIED CONDITIONTester Connection Specified Condition HA1A( E42-1) - HA1A (E6-6) Below 1 Ω A1A+ (E42-3) - A1A+ (E6-18) Below 1 Ω A1A- (E42-4) - A1A- (E6-17) Below 1 Ω HA2A (E38-1) - HA2A (E6-4) Below 1 Ω A2A+ (E38-3) - A2A+ (E6-28) Below 1 Ω A2A- (E38-4) - A2A- (E6-27) Below 1 Ω Standard resistance (Check for short)
TESTER CONNECTION SPECIFIED CONDITIONTester Connection Specified Condition HA1A( E42-1) or HA1A (E6-6) - Body ground 10 kΩ or higher A1A+ (E42-3) or A1A+ (E6-18) - Body ground 10 kΩ or higher A1A- (E42-4) or A1A- (E6-17) - Body ground 10 kΩ or higher HA2A (E38-1) or HA2A (E6-4) - Body ground 10 kΩ or higher A2A+ (E38-3) or A2A+ (E6-28) - Body ground 10 kΩ or higher A2A- (E38-4) or A2A- (E6-27) - Body ground 10 kΩ or higher - Reconnect the ECM connector.
- Reconnect the A/F sensor connector.
NG : REPAIR OR REPLACE HARNESS OR
OK : CONNECTOR
- REPLACE AIR FUEL RATIO SENSOR
NEXT
- PERFORM COMFORTABLE AIR SEAT SYSTEM
- Connect the intelligent tester to the DLC3.
- Turn the engine switch on (IG) and turn the tester on.
- Clear DTCs (See DIAGNOSIS SYSTEM ).
- Switch the ECM from normal mode to check mode using the tester (See DTC CHECK / CLEAR ).
- Start the engine and warm it up with all the accessories switched OFF. (Procedure "A")
- Drive the vehicle at between 38 mph and 75 mph (60 km/h and 120 km/h) and at an engine speed of between 1,400 rpm and 3,200 rpm for 3 to 5 minutes. (Procedure "B")
HINT:
If the system is still malfunctioning, the MIL will be illuminated during procedure "B".
NOTE: If the conditions in this test are not strictly followed, no malfunction will be detected.
NEXT
- CHECK WHETHER DTC OUTPUT RECURS (DTC P0171, P0172, P0174 OR P0175)
- On the intelligent tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
- Read DTCs.
Result
RESULT REFERENCEDisplay (DTC output) Proceed to No output A P0171, P0172, P0174 or P0175 B
A : END
B : GO TO NEXT STEP
- CHECK FUEL PRESSURE (LOW PRESSURE)
- Check the fuel pressure (See ON-VEHICLE INSPECTION ).
OK : REPLACE ECM
NG : GO TO NEXT STEP
- CHECK FUEL PUMP OPERATION
- Check the fuel pump operation (See ON-VEHICLE INSPECTION ).
NG : REPLACE FUEL PUMP
OK : GO TO NEXT STEP
- CHECK FUEL LEAKAGE (LOW PRESSURE SIDE)
OK: No leakage
NG : REPAIR OR REPLACE FUEL SYSTEM
OK : CHECK AND REPLACE FUEL PUMP, PRESSURE REGULATOR, FUEL PIPE LINE AND FILTER
- CHECK FUEL PRESSURE SENSOR
- Connect the intelligent tester to the DLC3.
- Turn the engine switch on (IG) and turn the tester on.
- Start the engine.
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / FUEL PRESS.
- While revving the engine, check that the fuel pressure fluctuates.
Standard:
- Idling: 3 to 5 MPa
- 2,500 rpm (No load): 6 to 10 MPa
HINT:
The A/C switch and all accessory switches should be OFF, and the transmission gear selector lever should be in the N or P position, and the engine should be fully warmed up.
NG : REPAIR OR REPLACE FUEL SYSTEM FOR HIGH PRESSURE (REFER TO DTC P0087 AND P0088 )
OK : GO TO NEXT STEP
- PERFORM SYSTEM CHECK (D-4S TEST)
- Connect the intelligent tester to the DLC3.
- Start the engine and turn the intelligent tester on.
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / SYSTEM CHECK / D-4S TEST / D-4S INJ SWITCH / PORT.
- Read the value SHORT FT #1 and LONG FT #1 and/or SHORT FT #2 and LONG FT #2.
OK: SHORT FT #1(#2) + LONG FT #1(#2) = Between - 19% and +19%
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / SYSTEM CHECK / D-4S TEST / D-4S INJ SWITCH / DIRECT.
HINT:
The A/C switch and all accessory switches should be OFF, and the transmission gear selector lever should be in the N or P position, and the engine should be fully warmed up.
- Read the value SHORT FT #1, LONG FT #1, SHORT FT #2, LONG FT #2 and FUEL PUMP D4.
Result
RESULT REFERENCEItem Proceed to FUEL PUMP D4 SHORT FT #1 + LONG FT #1 SHORT FT #2 + LONG FT #2 40% or more -20% or less -20% or less A 10% or less +20% or more +20% or more A 40% or more +20% or more +20% or more B 10% or less -20% or less -20% or less C 10% to 40% - - D
A : REPLACE FUEL PRESSURE SENSOR
B : Go to step 23
C : REPLACE ECM
D
- PERFORM SYSTEM CHECK (D-4S TEST)
- Connect the intelligent tester to the DLC3.
- Start the engine and turn the intelligent tester on.
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / SYSTEM CHECK / D-4S TEST / D-4S INJ SWITCH / PORT.
- Read the value SHORT FT #1 and LONG FT #1 and/or SHORT FT #2 and LONG FT #2.
OK: SHORT FT #1(#2) + LONG FT #1(#2) = Between - 19% and +19%
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / SYSTEM CHECK / D-4S TEST / D-4S INJ SWITCH / DIRECT.
HINT:
The A/C switch and all accessory switches should be OFF, and the transmission gear selector lever should be in the N or P position, and the engine should be fully warmed up.
- Read the value SHORT FT #1, LONG FT #1, SHORT FT #2, LONG FT #2 and FUEL PUMP D4.
Result
RESULT REFERENCEItem Proceed to FUEL PUMP D4 SHORT FT #1 + LONG FT #1 SHORT FT #2 + LONG FT #2 10% to 40% -25% or less -25% or less A 10% to 40% -25% or less -25% to +25% B 10% to 40% -25% to +25% -25% or less C 10% to 40% +30% or more +30% or more A 10% to 40% +25% or more -25% to +25% B 10% to 40% -25% to +25% +25% or more C 10% to 40% -25% to +25% -25% to +25% D
B : REPLACE FUEL INJECTOR FOR DIRECT INJECTION (BANK 1)
C : REPLACE FUEL INJECTOR FOR DIRECT INJECTION (BANK 2)
D : CHECK FOR INTERMITTENT PROBLEMS
A : REPLACE FUEL INJECTOR FOR DIRECT INJECTION (ALL CYLINDER)
- CHECK RELIEF VALVE
- Connect the intelligent tester to the DLC3.
- Turn the engine switch on (IG) and turn the tester on.
- Start the engine.
- Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / FUEL PRESS.
- Check that the fuel pressure fluctuates when the fuel hose is pressed with your fingers.
Result
RESULT REFERENCEInspection Result Proceed to Pressing the hose raises the fuel pressure slightly A Fuel pressure does not fluctuate B
OK : REPLACE RELIEF VALVE
B : REPLACE FUEL PUMP FOR HIGH PRESSURE
- CHECK FUEL INJECTOR FOR PORT INJECTION
- Check the injection volume (whether fuel volume is high or low, and whether injection pattern is poor).
NG : REPLACE FUEL INJECTOR FOR PORT INJECTION
OK : REPLACE ECM