DTC Code | DTC Name |
---|---|
P0171 | System Too Lean (Bank 1) |
P0172 | System Too Rich (Bank 1) |
P0174 | System Too Lean (Bank 2) |
P0175 | System Too Rich (Bank 2) |
P1170 | Port Injector Fuel Performance |
P117B | Direct Injector Fuel Performance |
DESCRIPTION
The fuel trim is related to the feedback compensation value, not to the basic injection time. The fuel trim consists of both the short-term and the long-term fuel trim.
The short-term fuel trim is fuel compensation that is used to constantly maintain the air fuel ratio at stoichiometric levels. The signal from the air fuel ratio sensor indicates whether the air fuel ratio is rich or lean compared to the stoichiometric ratio. This triggers a reduction in the fuel injection volume if the air fuel ratio is rich and an increase in the fuel injection volume if it is lean.
Factors such as individual engine differences, wear over time and changes in operating environment cause short-term fuel trim to vary from the ideal theoretical value. The long-term fuel trim controls overall fuel compensation. The long-term fuel trim compensates for long term deviations of the fuel trim from the ideal theoretical value. These long term deviations result from the corrections made by the short-term fuel trim.
If both the short-term fuel and long-term fuel trims are lean or rich beyond predetermined values, it is interpreted as a malfunction, and the ECM illuminates the MIL and sets a DTC.
DTC No. | DTC Detection Condition | Trouble Area |
---|---|---|
P0171 P0174 |
Fuel trim is too lean (2 trip detection logic) |
|
P0172 P0175 |
Fuel trim is too rich (2 trip detection logic) |
|
P1170 | With stable air fuel ratio feedback, a fuel injection system malfunction has been detected and fuel trim of the port injection is unusually rich or lean side. |
|
P117B | With stable air fuel ratio feedback, a fuel injection system malfunction has been detected and fuel trim of the direct injection is unusually rich or lean side. |
Tech Tips
If the vehicle runs out of fuel, the air fuel ratio is lean and DTC P0171 or P0174 may be set. The MIL is then illuminated.
MONITOR DESCRIPTION
Under closed-loop fuel control, fuel injection volumes that deviate from those estimated by the ECM cause changes in the long-term fuel trim compensation value. The long-term fuel trim is adjusted when there are persistent deviations in the short-term fuel trim values. Deviations from the ECM's estimated fuel injection volumes also affect the average fuel trim learning value, which is a combination of the average short-term fuel trim (fuel feedback compensation value) and the average long-term fuel trim (learning value of the air fuel ratio). If the average fuel trim learning value exceeds the malfunction threshold, the ECM interprets this as a fault in the fuel system and sets a DTC.
Example:
If the average fuel trim learning value is 35% or more or -35% or less, the ECM interprets this as a fuel system malfunction.
WIRING DIAGRAM
Refer to DTC P2195 Click here.
INSPECTION PROCEDURE
Tech Tips
Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F sensor function provided in the Active Test. The Control the Injection Volume for A/F sensor function can help to determine whether the air fuel ratio sensor, heated oxygen sensor and other potential trouble areas are malfunctioning.
The following instructions describe how to conduct the Control the Injection Volume for A/F sensor operation using the 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 2500 rpm for approximately 90 seconds.
On the intelligent tester, enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F sensor.
Perform the Active Test 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 air fuel ratio sensors and heated oxygen sensors (AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2) displayed on the tester.
Tech Tips
The Control the Injection Volume for A/F sensor 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 B1 S1 or AFS B2 S1 (Air fuel ratio) |
+25% | Rich | Less than 3.0 V |
AFS B1 S1 or AFS B2 S1 (Air fuel ratio) |
-12.5% | Lean | More than 3.35 V |
O2S B1 S2 or O2S B2 S2 (Heated oxygen) |
+25% | Rich | More than 0.55 V |
O2S B1 S2 or O2S B2 S2 (Heated oxygen) |
-12.5% | Lean | Less than 0.4 V |
Note
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.
Case | Air Fuel Ratio Sensor (Sensor 1) Output Voltage | Heated Oxygen Sensor (Sensor 2) Output Voltage | Main Suspected Trouble Area |
---|---|---|---|
1 | - | ||
2 |
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3 |
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4 |
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Following the Control the Injection Volume for A/F sensor procedure enables technicians to check and graph the voltage outputs of both the air fuel ratio sensors and heated oxygen sensors.
To display the graph, enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor / A/F Control System / AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2.
Tech Tips
Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.
A low air fuel ratio sensor voltage could be caused by a rich air fuel mixture. Check for conditions that would cause the engine to run rich.
A high air fuel ratio sensor voltage could be caused by a lean air fuel mixture. Check for conditions that would cause the engine to run lean.
PROCEDURE
CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0171, P0172, P0174, P0175, P1170 OR P117B)
Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG) and turn the tester ON.
Enter the following menus: Powertrain / Engine / DTC.
Read the DTCs.
Result | ||||||
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Tech Tips
If any DTCs other than P0171, P0172, P0174, P0175, P1170 or P117B are output, troubleshoot those DTCs first.
B |
GO TO DTC CHART Click here |
A |
READ VALUE USING INTELLIGENT TESTER
Connect the intelligent tester to the DLC3.
Start the engine and turn the tester ON.
Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Way / Port.
Read the value.
Select: Data List / A/F Control System / 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: Powertrain / Engine / Active Test / Control the Injection Way / Direct.
Read the value.
Select: Data List / A/F Control System / 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 | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
B |
CHECK FUEL PRESSURE SENSOR Click here |
C |
CHECK FUEL INJECTOR FOR PORT INJECTION Click here |
D |
CHECK PCV HOSE Click here |
A |
CHECK IF VEHICLE HAS RUN OUT OF FUEL IN PAST
Has the run out of fuel in the past?
NO |
CHECK FOR INTERMITTENT PROBLEMS Click here |
YES |
DTC CAUSED BY RUNNING OUT OF FUEL
CHECK PCV HOSE
OK |
---|
PCV hose is connected correctly and is not damaged. |
NG |
REPAIR OR REPLACE PCV HOSE Click here |
OK |
CHECK INTAKE SYSTEM
Check the intake system for vacuum leakage Click here.
OK |
---|
No leaks from intake system. |
NG |
REPAIR OR REPLACE INTAKE SYSTEM Click here |
OK |
PERFORM ACTIVE TEST USING 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 2500 rpm for approximately 90 seconds.
Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor.
Perform the Active Test 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 air fuel ratio sensors and heated oxygen sensors (AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2) displayed on the tester.
Tech Tips
The Control the Injection Volume for A/F sensor 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 B1 S1 or AFS B2 S1 (Air fuel ratio) |
+25% | Rich | Less than 3.0 V |
AFS B1 S1 or AFS B2 S1 (Air fuel ratio) |
-12.5% | Lean | More than 3.35 V |
O2S B1 S2 or O2S B2 S2 (Heated oxygen) |
+25% | Rich | More than 0.55 V |
O2S B1 S2 or O2S B2 S2 (Heated oxygen) |
-12.5% | Lean | Less than 0.4 V |
Result | ||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Lean:
During Control the Injection Volume for A/F sensor, the air fuel ratio sensor output voltage (AFS) is consistently more than 3.35 V, and the heated oxygen sensor output voltage (O2S) is consistently less than 0.4 V.
Rich:
During Control the Injection Volume for A/F sensor, the AFS is consistently less than 3.0 V, and the O2S is consistently more than 0.55 V.
B |
INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE) Click here |
A |
READ VALUE USING 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: Powertrain / Engine / Data List / All Data / Coolant Temp.
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 and 95°C (167 and 203°F) |
NG |
REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here |
OK |
INSPECT MASS AIR FLOW METER SUB-ASSEMBLY
Inspect the mass air flow meter sub-assembly Click here.
NG |
REPLACE MASS AIR FLOW METER SUB-ASSEMBLY Click here |
OK |
CHECK FOR EXHAUST GAS LEAK
Check for exhaust gas leaks.
OK |
---|
No gas leaks. |
NG |
REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT |
OK |
INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
Disconnect the air fuel ratio sensor connector.
Measure the resistance according to the value(s) in the table below.
Standard Resistance (Bank 1 Sensor 1) | |||||||||
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Standard Resistance (Bank 2 Sensor 1) | |||||||||
---|---|---|---|---|---|---|---|---|---|
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Reconnect the air fuel ratio sensor connector.
NG |
REPLACE AIR FUEL RATIO SENSOR Click here |
OK |
CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)
Disconnect the air fuel ratio sensor connectors.
Disconnect the ECM connectors.
Measure the resistance according to the value(s) in the table below.
Standard Resistance (Check for Open) | |||||||||||||||||||||
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Standard Resistance (Check for Short) | |||||||||||||||||||||
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Reconnect the ECM connector.
Reconnect the air fuel ratio sensor connectors.
NG |
REPAIR OR REPLACE HARNESS OR CONNECTOR |
OK |
REPLACE AIR FUEL RATIO SENSOR
Replace the air fuel ratio sensor Click here.
NEXT |
PERFORM CONFIRMATION DRIVING PATTERN
Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG) and turn the tester ON.
Clear the DTCs Click here.
Switch the ECM from normal mode to check mode using the tester Click here.
Start the engine and warm it up with all the accessories switched off. (Procedure "A")
Drive the vehicle at between 60 and 120 km/h (38 and 75 mph) and at an engine speed of between 1400 rpm and 3200 rpm for 3 to 5 minutes. (Procedure "B")
Tech Tips
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, P0175, P1170 OR P117B)
Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG) and turn the tester ON.
Enter the following menus: Powertrain / Engine / DTC.
Read the DTCs.
Result | ||||||
---|---|---|---|---|---|---|
|
A |
END |
B |
CHECK FUEL PRESSURE (LOW PRESSURE)
Check the fuel pressure Click here.
NG |
CHECK FUEL PUMP OPERATION Click here |
OK |
REPLACE ECM Click here
CHECK FUEL PUMP OPERATION
Check the fuel pump operation Click here.
NG |
REPAIR OR REPLACE FUEL PUMP CONTROL CIRCUIT Click here |
OK |
CHECK FUEL LEAK (LOW PRESSURE SIDE)
Check for fuel leaks Click here.
OK |
---|
No leaks. |
NG |
REPAIR OR REPLACE FUEL SYSTEM |
OK |
CHECK FUEL LINE
Check the fuel line for leaks or blockage.
OK |
---|
No leaks or blockage. |
NG |
REPAIR OR REPLACE FUEL LINE |
OK |
CHECK AND REPLACE FUEL SYSTEM (FUEL PRESSURE REGULATOR, FUEL 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: Powertrain / Engine / Data List / All Data / Fuel Press.
While revving the engine, check that the fuel pressure fluctuates.
Standard |
---|
Idling |
3.5 to 4.5 MPa (35.7 to 45.9 kgf/cm2, 508 to 653 psi) |
2000 rpm (No load) |
7 to 9 MPa (61.2 to 102.0 kgf/cm2, 1015 to 1305 psi) |
Tech Tips
The A/C switch and all accessory switches should be off, and the shift lever should be in N or P, and the engine should be fully warmed up.
NG |
CHECK MISFIRE COUNT Click here |
OK |
READ VALUE USING INTELLIGENT TESTER
Connect the intelligent tester to the DLC3.
Start the engine and turn the tester ON.
Enter the following menus: Powertrain / Engine / Active Test / Control the Injection way / Direct.
Tech Tips
The A/C switch and all accessory switches should be off, and the shift lever should be in N or P, and the engine should be fully warmed up.
Read the value.
Select: Data List / A/F Control System / Short FT #1, Long FT #1, Short FT #2, Long FT #2 and Fuel Pump Duty (D4).
Result | |||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
A |
REPLACE FUEL PRESSURE SENSOR Click here |
B |
INSPECT FUEL RELIEF VALVE ASSEMBLY Click here |
C |
REPLACE ECM Click here |
D |
READ VALUE USING INTELLIGENT TESTER
Connect the intelligent tester to the DLC3.
Start the engine and turn the tester ON.
Enter the following menus: Powertrain / Engine / Active Test / Control the Injection way / Direct.
Tech Tips
The A/C switch and all accessory switches should be OFF, and the shift lever should be in N or P, and the engine should be fully warmed up.
Read the value of Data List:
Select: Data List / A/F Control System / Short FT #1, Long FT #1, Short FT #2, Long FT #2 and Fuel Pump Duty (D4).
Result | |||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
B |
REPLACE FUEL INJECTOR FOR DIRECT INJECTION (BANK 1) Click here |
C |
REPLACE FUEL INJECTOR FOR DIRECT INJECTION (BANK 2) Click here |
D |
CHECK FOR INTERMITTENT PROBLEMS Click here |
A |
REPLACE FUEL INJECTOR FOR DIRECT INJECTION (ALL CYLINDERS) Click here
CHECK MISFIRE COUNT
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: Powertrain / Engine / Active Test / Control the Injection Way / Direct.
Allow the engine to idle.
Monitor all of the misfire count values that are displayed on the tester: Powertrain / Engine / Data List / Misfire / Cylinder #1 Misfire Count to Cylinder #8 Misfire Count.
If no misfire counts occur for any of the cylinders, perform the following procedure:
Move the shift lever to D.
Monitor all of the misfire count values that are displayed on the tester.
Result | ||||||
---|---|---|---|---|---|---|
|
B |
REPLACE FUEL INJECTOR FOR DIRECT INJECTION Click here |
A |
INSPECT INJECTOR DRIVER (NO. 1 AND NO. 2)
Turn the engine switch off.
Replace the No. 1 and No. 2 injector drivers with normal ones from another vehicle.
Note
Do not disconnect and reconnect the connectors with the engine switch on (IG), as the injector driver (EDU) may be damaged.
Connect the intelligent tester to the DLC3.
Start the engine.
Clear the DTCs Click here.
Perform the driving test.
Enter the following menus: Powertrain / Engine / DTC.
Read the DTCs.
Result | ||||||
---|---|---|---|---|---|---|
|
B |
REPLACE INJECTOR DRIVER (NO. 1 AND NO. 2) Click here |
A |
INSPECT FUEL RELIEF VALVE ASSEMBLY
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: Powertrain / Engine / Data List / All Data / Fuel Press.
Write down the Fuel Press value.
Turn the engine switch off.
Wait for 10 seconds.
Turn the engine switch on (IG) and turn the tester ON.
Enter the following menus: Powertrain / Engine / Data List / All Data / Fuel Press.
Compare the Fuel Press value from and the fuel pressure value after the engine switch was turned on (IG).
Result | ||||||
---|---|---|---|---|---|---|
|
A |
REPLACE FUEL RELIEF VALVE ASSEMBLY Click here |
B |
REPLACE FUEL PUMP FOR HIGH PRESSURE Click here
CHECK FUEL INJECTOR FOR PORT INJECTION
Check the injection volume (whether fuel volume is high or low, and whether injection pattern is poor) Click here.
NG |
REPLACE FUEL INJECTOR FOR PORT INJECTION Click here |
OK |
REPLACE ECM Click here