DTC detecting condition | Trouble area |
---|---|
DTC P0171:
Total fuel trim is higher than 35% or short term fuel trim is higher than 20% for more than 1 min. continuously. (2 driving cycle detection logic) DTC P0172: Total fuel trim is lower than –35% or short term fuel trim is lower than –20% for more than 1 min. continuously. (2 driving cycle detection logic) |
•
Vacuum leaks
• Exhaust gas leakage • Fuel pressure out of specification • Fuel injector malfunction • Heated oxygen sensor-1 malfunction • MAF sensor malfunction • ECT sensor malfunction |
Step | Action | YES | NO |
---|---|---|---|
1 |
Was “Engine and Emission Control System Check” performed?
|
Go to Step 2.
|
|
2 |
Is there DTC(s) other than fuel system (DTC P0171/P0172)?
|
Go to applicable DTC diag. flow.
|
Go to Step 3.
|
3 |
Intake system and exhaust system for leakage check
Are intake system and exhaust system in good condition?
|
Go to Step 4.
|
Repair or replace.
|
4 |
Fuel pressure check
1)
Check fuel pressure referring to
Fuel Pressure Inspection:M13A
.
Is check result satisfactory?
|
Go to Step 5.
|
Repair or replace.
|
5 |
Fuel injectors and its circuit check
1)
Check fuel injectors referring to
Fuel Injector Inspection:M13A
.
Is check result satisfactory?
|
Go to Step 6.
|
Faulty injector(s) or its circuit.
|
6 |
Visual inspection
1)
Check MAF sensor and air intake system.
•
Objects which block measuring duct and resistor of MAF sensor.
• Other air flow which does not pass the MAF sensor.
Are there in good condition?
|
Go to Step 7.
|
Repair or replace.
|
7 |
MAF sensor for performance check
1)
With ignition switch turned OFF, install scan tool.
2)
Start engine and warm up to normal operating temperature.
3)
Check MAF value using scan tool (Refer to
Scan Tool Data:M13A with VVT
for normal value.).
Is each value within specified?
|
Go to Step 8.
|
|
8 |
ECT sensor for performance check
1)
Check ECT sensor referring to Step 3 and 4 of
DTC P0118: Engine Coolant Temperature Circuit High:M13A with VVT
.
Is check result satisfactory?
|
Go to Step 9.
|
Faulty ECT sensor or its circuit.
|
9 |
HO2S-1 for performance check
1)
Check HO2S-1 referring to Step 3 of
DTC P0131 / P0132: O2 Sensor (HO2S) Circuit Low Voltage / High Voltage (Sensor-1):M13A with VVT
.
Is check result satisfactory?
|
Substitute a known-good ECM and recheck.
|
Faulty HO2S-1 or its circuit.
|