P0175
2UR-FSE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0171,P0172,P0174,P0175: System Too Lean (Bank 1)
P0175 - System Too Rich (Bank 2)
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 (A/F) 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.
HINT
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.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
Fuel-trim:
WIRING DIAGRAM
Refer to DTC P2195 P2195.
INSPECTION PROCEDURE
HINT
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 (A/F) sensor, Heated Oxygen (HO2) 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 Techstream.
(a) Connect the Techstream to the DLC3.
(b) Put the engine in inspection mode Inspection Mode Procedure.
(c) Turn the Techstream ON.
(d) Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
(e) On the Techstream, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F sensor.
(f) Perform the Active Test operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
(g) Monitor the output voltages of the A/F and HO2 sensors (AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2) 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 25%.
- Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
NOTICE:
The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO2) sensor has a maximum output delay of approximately 20 seconds.
- Following the Control the Injection Volume for A/F sensor 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: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / A/F Control System / AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2.
HINT
- When viewed from the rear of the engine assembly, Bank 1 is on the left side and Bank 2 is on the right side.
- Read freeze frame data using the Techstream. 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 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 lean air-fuel mixture. Check for conditions that would cause the engine to run lean.
PROCEDURE
1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0171, P0172, P0174 OR P0175)
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG) and turn the Techstream ON.
(c) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(d) Read DTCs.
Result
HINT
If any DTCs other than P0171, P0172, P0174 or P0175 are output, troubleshoot those DTCs first.
B -- GO TO DTC CHART SFI System
A -- Continue to next step.
2. READ VALUE USING TECHSTREAM
(a) Connect the Techstream to the DLC3.
(b) Put the engine in inspection mode Inspection Mode Procedure.
(c) Turn the Techstream ON.
(d) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Way / Port.
(e) Read the value.
(1) Enter the following menus: Powertrain / Engine and ECT / 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%
(f) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Way / Direct.
(g) Read the value.
(1) Enter the following menus: Powertrain / Engine and ECT / 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
D -- CHECK PCV HOSE
C -- CHECK FUEL INJECTOR FOR PORT INJECTION
B -- CHECK FUEL PRESSURE SENSOR
A -- Continue to next step.
3. CHECK FOR INTERMITTENT PROBLEMS
HINT
By repeating short trips*, when warming up the engine, gasoline evaporates and blow-by gas increases. As a result, DTC P0172 and/or DTC P0175 may be output.
*: Driving time (distance) from turning the power switch on (READY) until turning it off is short.
NEXT -- END
4. CHECK PCV HOSE
OK:
PCV hose is connected correctly and is not damaged.
NG -- REPAIR OR REPLACE PCV HOSE Removal
OK -- Continue to next step.
5. CHECK AIR INDUCTION SYSTEM
(a) Check the air induction system for vacuum leakage Testing and Inspection.
OK:
No leakage from air induction system.
NG -- REPAIR OR REPLACE AIR INDUCTION SYSTEM Removal
OK -- Continue to next step.
6. PERFORM ACTIVE TEST USING TECHSTREAM
(a) Connect the Techstream to the DLC3.
(b) Put the engine in inspection mode Inspection Mode Procedure.
(c) Turn the Techstream ON.
(d) Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
(e) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
(f) Perform the Active Test operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
(g) Monitor the output voltages of the A/F and HO2 sensors (AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2) 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 25%.
- Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
Result
Lean:
* During Control the Injection Volume for A/F sensor, the A/F sensor output voltage (AFS) is consistently more than 3.4 V, and the HO2 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 3.1 V, and the O2S is consistently more than 0.55 V.
B -- REPLACE AIR FUEL RATIO SENSOR
A -- Continue to next step.
7. READ VALUE USING TECHSTREAM (COOLANT TEMP)
(a) Connect the Techstream to the DLC3.
(b) Put the engine in inspection mode Inspection Mode Procedure.
(c) Turn the Techstream ON.
(d) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Coolant Temp.
(e) 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 Removal
OK -- Continue to next step.
8. INSPECT MASS AIR FLOW METER (for Bank 1 and Bank 2)
(a) Inspect the mass air flow meter Removal.
NG -- REPLACE MASS AIR FLOW METER Removal
OK -- Continue to next step.
9. INSPECT FOR EXHAUST GAS LEAK
OK:
No gas leakage.
NG -- REPAIR OR REPLACE EXHAUST SYSTEM
OK -- Continue to next step.
10. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE) P0031
NG -- REPLACE AIR FUEL RATIO SENSOR Removal
OK -- Continue to next step.
11. CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)
(a) Disconnect the E47 and E48 A/F sensor connectors.
(b) Turn the power switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:
(d) Turn the power switch off.
(e) Disconnect the E3 and E4 ECM connectors.
(f) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):
Standard resistance (Check for short):
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
12. REPLACE AIR FUEL RATIO SENSOR
(a) Replace the air fuel ratio sensor Removal.
NEXT -- Continue to next step.
13. PERFORM CONFIRMATION DRIVING PATTERN
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG) and turn the Techstream ON.
(c) Clear DTCs DTC Check / Clear.
(d) Turn the power switch on (READY).
(e) Switch the ECM from normal mode to check mode using the Techstream Inspection Mode Procedure.
(f) Warm it up with all the accessories switched OFF. (Procedure "A")
(g) Drive the vehicle at between 60 km/h and 120 km/h (38 mph and 75 mph) and at an engine speed of between 1400 rpm and 3200 rpm for 10 minutes. (Procedure "B")
HINT
If the system is still malfunctioning, the MIL will be illuminated during procedure "B".
NOTICE:
If the conditions in this test are not strictly followed, no malfunction will be detected.
NEXT -- Continue to next step.
14. CHECK WHETHER DTC OUTPUT RECURS (DTC P0171, P0172, P0174 OR P0175)
(a) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(b) Read the DTCs.
Result
A -- END
B -- Continue to next step.
15. CHECK FUEL PRESSURE (LOW PRESSURE)
(a) Check the fuel pressure Testing and Inspection.
NG -- CHECK FUEL PUMP OPERATION
OK -- REPLACE ECM Removal
16. CHECK FUEL PUMP OPERATION
(a) Check the fuel pump operation Testing and Inspection.
NG -- REPLACE FUEL PUMP Removal
OK -- Continue to next step.
17. INSPECT FOR FUEL LEAK (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
18. CHECK FUEL PRESSURE SENSOR
(a) Connect the Techstream to the DLC3.
(b) Put the engine in inspection mode Inspection Mode Procedure.
(c) Turn the Techstream ON.
(d) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Fuel Press.
(e) While revving the engine, check that the fuel pressure fluctuates.
Standard:
Idling
3500 to 4500 kPa
2500 rpm (No load)
7000 to 9000 kPa
HINT
The A/C switch and all accessory switches should be OFF, the shift 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) SFI System
OK -- Continue to next step.
19. READ VALUE USING TECHSTREAM
(a) Connect the Techstream to the DLC3.
(b) Put the engine in inspection mode Inspection Mode Procedure.
(c) Turn the Techstream ON.
(d) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection way / Direct.
HINT
The A/C switch and all accessory switches should be OFF, the shift lever should be in the N or P position, and the engine should be fully warmed up.
(e) Read the value.
(1) Enter the following menus: Powertrain / Engine and ECT / Data List / A/F Control System / Short FT #1, Long FT #1, Short FT #2, Long FT #2 and Fuel Pump Duty (D4).
Result
C -- REPLACE ECM Removal
B -- INSPECT FUEL RELIEF VALVE
A -- REPLACE FUEL PRESSURE SENSOR Removal
D -- Continue to next step.
20. READ VALUE USING TECHSTREAM
(a) Connect the Techstream to the DLC3.
(b) Put the engine in inspection mode Inspection Mode Procedure.
(c) Turn the Techstream ON.
(d) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection way / Direct.
HINT
The A/C switch and all accessory switches should be OFF, the shift lever should be in the N or P position, and the engine should be fully warmed up.
(e) Read the value.
(1) Enter the following menus: Powertrain / Engine and ECT / Data List / A/F Control System / Short FT #1, Long FT #1, Short FT #2, Long FT #2 and Fuel Pump Duty (D4).
Result
D -- CHECK FOR INTERMITTENT PROBLEMS Check For Intermittent Problems
C -- REPLACE FUEL INJECTOR FOR DIRECT INJECTION (for Bank 2) Removal
B -- REPLACE FUEL INJECTOR FOR DIRECT INJECTION (for Bank 1) Removal
A -- REPLACE FUEL INJECTOR FOR DIRECT INJECTION (ALL CYLINDERS) Removal
21. INSPECT FUEL RELIEF VALVE
(a) Put the engine in inspection mode Inspection Mode Procedure.
(b) Warm up the engine.
(c) Connect the Techstream to the DLC3.
(d) Turn the Techstream ON.
(e) Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / Fuel Press and Coolant Temp and Battery Voltage.
HINT
- Coolant Temp value is 50°C (122°F) or more
- Battery Voltage value is 10 V or more
- Fuel Press value is 2 MPa or more
(f) Turn the power switch off.
(g) Wait for 10 seconds.
(h) Put the engine in inspection mode.
(i) Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / Fuel Press.
(j) After starting the engine, turn the power switch off within 45 seconds.
HINT
Before turning the power switch off, write down the Fuel Press value.
(k) Wait for 10 seconds. Then turn the power switch on (IG).
(l) Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / Fuel Press.
(m) Check the fuel pressure.
OK:
Fuel pressure is stable.
NG -- REPLACE FUEL RELIEF VALVE Removal
OK -- REPLACE FUEL PUMP FOR HIGH PRESSURE Removal
22. CHECK FUEL INJECTOR FOR PORT INJECTION
(a) Check the injection volume (whether fuel volume is high or low, and whether injection pattern is poor) Fuel Injector (for Port Injection).
NG -- REPLACE FUEL INJECTOR FOR PORT INJECTION Removal
OK -- REPLACE ECM Removal