SFI SYSTEM (w/o EGR System), Diagnostic DTC:P0171, P0172, P0174, P0175

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)

DESCRIPTION

The fuel trim is related to the feedback compensation value, not to the basic injection duration. The fuel trim consists of both the short-term and 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 central value. The long-term fuel trim, which controls overall fuel compensation, compensates for long-term deviations in the fuel trim from the central value caused by the short-term fuel trim compensation.

If both the short-term and long-term fuel trim 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	With warm engine and stable air fuel ratio feedback, fuel trim considerably in error to lean side (2 trip detection logic)	Intake system Fuel injector assembly Mass air flow meter sub-assembly Engine coolant temperature sensor Fuel pressure Gas leaks from exhaust system Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit Air fuel ratio sensor (bank 1, 2 sensor 1) A/F relay A/F fuse PCV valve and hose PCV hose connections Wire harness or connector ECM
P0172 P0175	With warm engine and stable air fuel ratio feedback, fuel trim considerably in error to rich side (2 trip detection logic)	Fuel injector assembly Mass air flow meter sub-assembly Engine coolant temperature sensor Ignition system Fuel pressure Gas leaks from exhaust system Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit Air fuel ratio sensor (bank 1, 2 sensor 1) A/F relay A/F fuse Wire harness or connector ECM

DTC No.

DTC Detection Condition

Trouble Area

P0171

P0174

With warm engine and stable air fuel ratio feedback, fuel trim considerably in error to lean side (2 trip detection logic)

Intake system
Fuel injector assembly
Mass air flow meter sub-assembly
Engine coolant temperature sensor
Fuel pressure
Gas leaks from exhaust system
Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit
Air fuel ratio sensor (bank 1, 2 sensor 1)
A/F relay
A/F fuse
PCV valve and hose
PCV hose connections
Wire harness or connector
ECM

P0172

P0175

With warm engine and stable air fuel ratio feedback, fuel trim considerably in error to rich side (2 trip detection logic)

Fuel injector assembly
Mass air flow meter sub-assembly
Engine coolant temperature sensor
Ignition system
Fuel pressure
Gas leaks from exhaust system
Open or short in air fuel ratio sensor (bank 1, 2 sensor 1) circuit
Air fuel ratio sensor (bank 1, 2 sensor 1)
A/F relay
A/F fuse
Wire harness or connector
ECM

Tech Tips

When DTC P0171 or P0174 is set, the actual air fuel ratio is on the lean side. When DTC P0172 or P0175 is set, the actual air fuel ratio is on the rich side.
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.
When the total of the short-term and long-term fuel trim values is within the malfunction threshold (and the engine coolant temperature is more than 75°C (167°F)), the system is functioning normally.

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 thresholds, the ECM interprets this as a fault in the fuel system and sets a DTC.

Example:

When the average fuel trim learning value is more than +35% or less than -35%, the ECM interprets this as a fuel system malfunction.

CONFIRMATION DRIVING PATTERN

Connect the intelligent tester to the DLC3.
Turn the power switch on (IG) and turn the tester on.
Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) Click here.
Turn the power switch off.
Turn the power switch on (IG) and turn the tester on [A].
Put the engine in inspection mode Click here.
Start the engine and warm it up (until the engine coolant temperature is 75°C (167°F) or more) with all the accessories switched off [B].
With the engine warmed up, idle the engine for 2 minutes or more [C].
Drive the vehicle at between 60 and 120 km/h (37 and 75 mph) and at an engine speed of between 1400 rpm and 2500 rpm for 5 minutes or more [D].

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Enter the following menus: Powertrain / Engine and ECT / DTC / Pending [E].
Read the pending DTC.

Tech Tips

If a pending DTC is output, the system is malfunctioning.

WIRING DIAGRAM

Refer to DTC P2195 Click here.

INSPECTION PROCEDURE

Tech Tips

Malfunctioning areas can be identified by performing the Control the Injection Volume function provided in the Active Test. The Control the Injection Volume 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 operation using the intelligent tester.

Connect the intelligent tester to the DLC3.
Turn the power switch on (IG).
Turn the tester on.
Put the engine in inspection mode Click here.
Start the engine.
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.

Tech Tips

During charging 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 charging control has completed.
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.
Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).
Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2) displayed on the tester.

Tech Tips

Change the fuel injection volume within the range of -12% to +12%. The injection volume can be changed in fine gradations.
Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS Voltage B1S1 AFS Voltage B2S1 (Air fuel ratio)	+12%	Rich	Below 3.1 V
AFS Voltage B1S1 AFS Voltage B2S1 (Air fuel ratio)	-12%	Lean	Higher than 3.4 V
O2S B1S2 O2S B2S2 (Heated oxygen)	+12%	Rich	Higher than 0.55 V
O2S B1S2 O2S B2S2 (Heated oxygen)	-12%	Lean	Below 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			Air fuel ratio sensor Air fuel ratio sensor heater Air fuel ratio sensor circuit
3			Heated oxygen sensor Heated oxygen sensor heater Heated oxygen sensor circuit
4			Fuel injector assembly Fuel pressure Gas leak from exhaust system (Air fuel ratio extremely rich or lean)

Following the Control the Injection Volume procedure enables technicians to check and graph the voltage outputs of both the air fuel ratio and heated oxygen sensors.
To display the graph, 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; and then press the graph button on the Data List view.

Note

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

Tech Tips

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 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 OR P0175)

Connect the intelligent tester to the DLC3.
Turn the power switch on (IG).
Turn the tester on.
Enter the following menus: Powertrain / Engine and ECT / DTC.

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

Tech Tips

If any DTCs other than P0171, P0172, P0174 or P0175 are output, troubleshoot those DTCs first.

GO TO DTC CHART Click here

CHECK PCV HOSE (HOSE CONNECTIONS)
1. Check the PCV hose connections Click here.
  
  OK
  
  PCV hose is connected correctly and is not damaged.
NG
REPAIR OR REPLACE PCV HOSE

OK
CHECK INTAKE SYSTEM
1. Check the intake system for vacuum leaks Click here.
  
  OK
  
  No leaks in intake system.
NG
REPAIR OR REPLACE INTAKE SYSTEM

OK

OK
PCV hose is connected correctly and is not damaged.

OK
No leaks in intake system.

PERFORM ACTIVE TEST USING INTELLIGENT TESTER (CONTROL THE INJECTION VOLUME)

Connect the intelligent tester to the DLC3.
Turn the power switch on (IG).
Turn the tester on.
Put the engine in inspection mode Click here.
Start the engine.
Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.

Tech Tips

During charging 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 charging control has completed.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume.
Perform the Control the Injection Volume operation with the engine in an idling condition.

Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2) displayed on the tester.

Tech Tips

Change the fuel injection volume within the range of - 12.0% to +12.0%. 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.

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS Voltage B1S1 or AFS Voltage B2S1 (Air fuel ratio)	+12%	Rich	Below 3.1 V
AFS Voltage B1S1 or AFS Voltage B2S1 (Air fuel ratio)	-12%	Lean	Higher than 3.4 V
O2S B1S2 or O2S B2S2 (Heated oxygen)	+12%	Rich	Higher than 0.55 V
O2S B1S2 or O2S B2S2 (Heated oxygen)	-12%	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 leaks from exhaust system Intake system Fuel pressure Mass air flow meter sub-assembly Engine coolant temperature sensor	A
Rich	Rich	Actual air fuel ratio rich	Fuel injector assembly leakage or blockage Gas leaks 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	B
Rich	Lean/Rich	Air fuel ratio sensor malfunction	Air fuel ratio sensor	B

Lean: During the Control the Injection Volume for A/F Sensor Active Test, the air fuel ratio sensor output voltage (AFS Voltage) is consistently more than 3.4 V, and the heated oxygen sensor output voltage (O2S) is consistently less than 0.4 V.

Rich: During the Control the Injection Volume for A/F Sensor Active Test, the AFS Voltage is consistently less than 3.1 V, and the O2S is consistently more than 0.55 V.

Lean/Rich: During the Control the Injection Volume for A/F Sensor Active Test, the output voltage of the heated oxygen sensor alternates correctly.

Tech Tips

Refer to "Data List / Active Test" [AFS Voltage B1S1, AFS Voltage B2S1, O2S B1S2 and O2S B2S2] Click here.

INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE) Click here

READ VALUE USING INTELLIGENT TESTER (COOLANT TEMP)

Connect the intelligent tester to the DLC3.
Turn the power switch on (IG).
Turn the tester on.
Enter the following menus: Powertrain / Engine and ECT / 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°C and 95°C (167°F and 203°F)

REPLACE ENGINE COOLANT TEMPERATURE SENSOR Click here

READ VALUE USING INTELLIGENT TESTER (MAF)
1. Connect the intelligent tester to the DLC3.
2. Turn the power switch on (IG).
3. Turn the tester on.
4. Put the engine in inspection mode Click here.
5. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF and Coolant Temp.
6. Allow the engine to idle until Coolant Temp reaches 75°C (167°F) or higher.
7. Read MAF with the engine speed at 2500 rpm.
  
  Standard
  
  Between 6 gm/sec and 17 gm/sec (shift lever: P).
  
  Tech Tips
  
  During charging 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 charging control has completed.
NG
CHECK HARNESS AND CONNECTOR ((MASS AIR FLOW METER SUB-ASSEMBLY CONNECTOR CONNECTION) Click here

OK
CHECK FUEL PRESSURE
1. Check the fuel pressure Click here.
NG
REPAIR OR REPLACE FUEL SYSTEM

OK
INSPECT FOR EXHAUST GAS LEAK
1. Inspect for exhaust gas leaks from the exhaust manifold sub-assembly and exhaust pipes.
  
  OK
  
  No gas leaks
NG
REPAIR OR REPLACE EXHAUST GAS LEAK POINT

OK
CHECK FOR SPARKS AND IGNITION
1. Perform a spark test.
  Tech Tips
  - Refer to the ignition system inspection procedure Click here.
  - If the spark plugs or ignition system malfunctions, engine misfire may occur. The misfire count can be read using the intelligent tester. Enter the following menus: Powertrain / Engine and ECT / Data List / Cylinder #1 Misfire Count (to Cylinder #4 Misfire Count).
NG
REPAIR OR REPLACE IGNITION SYSTEM

OK
INSPECT FUEL INJECTOR ASSEMBLY (INJECTION VOLUME)
1. Inspect the fuel injector assembly Click here.
OK
PERFORM CONFIRMATION DRIVING PATTERN Click here

NG
REPLACE FUEL INJECTOR ASSEMBLY Click here
INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
1. Inspect the air fuel ratio sensor Click here.
NG
REPLACE AIR FUEL RATIO SENSOR Click here

OK

Standard
Between 6 gm/sec and 17 gm/sec (shift lever: P).

OK
No gas leaks

CHECK TERMINAL VOLTAGE (+B TERMINAL OF AIR FUEL RATIO SENSOR)

Text in Illustration
*1	Bank 1
*2	Bank 2
*a	Front view of wire harness connector (to Air Fuel Ratio Sensor)

Disconnect the air fuel ratio sensor connector.

Turn the power switch on (IG).

Measure the voltage according to the value(s) in the table below.

Standard Voltage

Tester Connection	Switch Condition	Specified Condition
D20-2 (+B) - Body ground	Power switch on (IG)	11 to 14 V
D19-2 (+B) - Body ground	Power switch on (IG)	11 to 14 V

Reconnect the air fuel ratio sensor connector.

Click here

CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)

Disconnect the air fuel ratio sensor connector.
Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
D20-1 (HA1A) - D1-24 (HA1A)	Always	Below 1 Ω
D20-3 (A1A+) - D1-100 (A1A+)	Always	Below 1 Ω
D20-4 (A1A-) - D1-132 (A1A-)	Always	Below 1 Ω
D19-1 (HA2A) - D1-22 (HA2A)	Always	Below 1 Ω
D19-3 (A2A+) - D1-99 (A2A+)	Always	Below 1 Ω
D19-4 (A2A-) - D1-131 (A2A-)	Always	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
D20-1 (HA1A) or D1-24 (HA1A) - Body ground	Always	10 kΩ or higher
D20-3 (A1A+) or D1-100 (A1A+) - Body ground	Always	10 kΩ or higher
D20-4 (A1A-) or D1-132 (A1A-) - Body ground	Always	10 kΩ or higher
D19-1 (HA2A) or D1-22 (HA2A) - Body ground	Always	10 kΩ or higher
D19-3 (A2A+) or D1-99 (A2A+) - Body ground	Always	10 kΩ or higher
D19-4 (A2A-) or D1-131 (A2A-) - Body ground	Always	10 kΩ or higher

Reconnect the air fuel ratio sensor connector.
Reconnect the ECM connector.

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

REPLACE AIR FUEL RATIO SENSOR
1. Replace the air fuel ratio sensor Click here.
NEXT

PERFORM CONFIRMATION DRIVING PATTERN

Connect the intelligent tester to the DLC3.
Turn the power switch on (IG).
Turn the tester on.
Clear the DTCs Click here.
Turn the power switch off.
Turn the power switch on (IG) and turn the tester on.
Put the engine in inspection mode Click here.
Start the engine and warm it up.
Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

Enter the following menus: Powertrain / Engine and ECT / DTC / Pending.

Result

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

END

CHECK HARNESS AND CONNECTOR ((MASS AIR FLOW METER SUB-ASSEMBLY CONNECTOR CONNECTION)
1. Check the connection and terminal contact pressure of connectors and wire harnesses between the mass air flow meter sub-assembly and ECM Click here.
  
  Tech Tips
  
  Repair any problems.
NEXT

CHECK WHETHER DTC OUTPUT RECURS

Connect the intelligent tester to the DLC3.
Turn the power switch on (IG).
Turn the tester on.
Clear the DTCs Click here.
Turn the power switch off.
Turn the power switch on (IG) and turn the tester on.
Put the engine in inspection mode Click here.
Start the engine and warm it up.
Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

Enter the following menus: Powertrain / Engine and ECT / DTC / Pending.

Result

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

END

CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)

Disconnect the mass air flow meter sub-assembly connector.
Disconnect the ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
D3-5 (VG) - D1-121 (VG)	Always	Below 1 Ω
D3-4 (E2G) - D1-120 (E2G)	Always	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
D3-5 (VG) or D1-121 (VG) - Body ground	Always	10 kΩ or higher

Reconnect the mass air flow meter sub-assembly connector.
Reconnect the ECM connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE MASS AIR FLOW METER SUB-ASSEMBLY
1. Replace the mass air flow meter sub-assembly Click here.
  
  Tech Tips
  
  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.
NEXT

CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

Connect the intelligent tester to the DLC3.
Turn the power switch on (IG).
Turn the tester on.
Clear the DTC Click here.
Turn the power switch off.
Turn the power switch on (IG) and turn the tester on.
Put the engine in inspection mode Click here.
Start the engine and warm it up.
Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

Enter the following menus: Powertrain / Engine and ECT / DTC / Pending.

Result

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

REPLACE ECM Click here

END

CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ENGINE ROOM JUNCTION BLOCK ASSEMBLY)

Disconnect the air fuel ratio sensor connector.
Remove the engine room junction block assembly.
Disconnect the engine room junction block assembly connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
D20-2 (+B) - 3C-2 (Engine room junction block assembly)	Always	Below 1 Ω
D19-2 (+B) - 3C-2 (Engine room junction block assembly)	Always	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
D20-2 (+B) or 3C-2 (Engine room junction block assembly) - Body ground	Always	10 kΩ or higher
D19-2 (+B) or 3C-2 (Engine room junction block assembly) - Body ground	Always	10 kΩ or higher

Reconnect the engine room junction block assembly connector.
Reinstall the engine room junction block assembly.
Reconnect the air fuel ratio sensor connector.

REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR FUEL RATIO SENSOR - ENGINE ROOM JUNCTION BLOCK ASSEMBLY)

CHECK TERMINAL VOLTAGE (ENGINE ROOM JUNCTION BLOCK ASSEMBLY)

Text in Illustration
*1	Engine Room Junction Block Assembly
*a	Front view of wire harness connector (to Engine Room Junction Block Assembly)

Remove the engine room junction block assembly.

Disconnect the engine room junction block assembly connector.

Measure the voltage according to the value(s) in the table below.

Standard Voltage

Tester Connection	Condition	Specified Condition
3A-1 (Engine room junction block assembly) - Body ground	Always	11 to 14 V

Reconnect the engine room junction block assembly connector.
Reinstall the engine room junction block assembly.

REPAIR OR REPLACE HARNESS OR CONNECTOR (ENGINE ROOM JUNCTION BLOCK ASSEMBLY - BATTERY)

CHECK HARNESS AND CONNECTOR (ENGINE ROOM JUNCTION BLOCK ASSEMBLY - EFI MAIN RELAY)

Remove the engine room junction block assembly.
Disconnect the engine room junction block assembly connector.
Remove the EFI MAIN relay from the engine room relay block.

Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
3C-7 (Engine room junction block assembly) - EFI MAIN relay terminal 3	Always	Below 1 Ω

Standard Resistance (Check for Short)

Tester Connection	Condition	Specified Condition
3C-7 (Engine room junction block assembly) or EFI MAIN relay terminal 3 - Body ground	Always	10 kΩ or higher

Reinstall the EFI MAIN relay.
Reconnect the engine room junction block assembly connector.
Reinstall the engine room junction block assembly.

REPAIR OR REPLACE HARNESS OR CONNECTOR (ENGINE ROOM JUNCTION BLOCK ASSEMBLY - EFI MAIN RELAY)

CHECK HARNESS AND CONNECTOR (ENGINE ROOM JUNCTION BLOCK ASSEMBLY - BODY GROUND)

Remove the engine room junction block assembly.
Disconnect the engine room junction block assembly connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Open)

Tester Connection	Condition	Specified Condition
3C-17 (Engine room junction block assembly) - Body ground	Always	Below 1 Ω

Reconnect the engine room junction block assembly connector.
Reinstall the engine room junction block assembly.

REPAIR OR REPLACE HARNESS OR CONNECTOR (ENGINE ROOM JUNCTION BLOCK ASSEMBLY - BODY GROUND)

REPLACE ENGINE ROOM JUNCTION BLOCK ASSEMBLY