P0171
P0171, P0174 Fuel Injection System FunctionOn Board Diagnosis Logic
With the Air-Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the theoretical mixture ratio based on the mixture ratio feedback signal from the air fuel ratio (A/F) sensor 1. The ECM calculates the necessary compensation to correct the offset between the actual and the
theoretical ratios.
In case the amount of the compensation value is extremely large (the actual mixture ratio is too lean), the ECM judges the condition as the fuel injection system malfunction and illuminates the MIL (2 trip detection logic).
P0171-P0174:
DTC Confirmation Procedure
NOTE: If DTC Confirmation Procedure has been previously conducted, always perform the following before conducting the next step.
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
WITH SDT
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Turn ignition switch ON and select "SELF-LEARNING CONT" in "Utility" mode with SDT.
6. Clear the self-learning control coefficient by touching "Clear".
7. Start engine again and let it idle for at least 5 minutes.
8. Check 1st trip DTC.
The 1st trip DTC P0171 or P0174 should be detected at this stage, if a malfunction exists. If so, go to [P0171, P0174 Fuel Injection System Function].
NOTE: If 1st trip DTC is not detected during above procedure, performing the following procedure is advised.
a. Turn ignition switch OFF and wait at least 10 seconds.
b. Start engine.
c. Maintain the following conditions for at least 10 consecutive minutes. Hold the accelerator pedal as steady as possible.
VHCL SPEED SE 50 - 120 km/h (31 - 75 mph)
CAUTION: Always drive vehicle at a safe speed.
9. If it is difficult to start engine at step 6, the fuel injection system has a malfunction, too.
10. Crank engine while depressing accelerator pedal. If engine starts, go to [P0171, P0174 Fuel Injection System Function]. If engine does not start, check exhaust and intake air leak visually.
WITH GST
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON.
4. Turn ignition switch OFF and wait at least 10 seconds.
5. Disconnect mass air flow sensor harness connector.
6. Restart engine and let it idle for at least 5 seconds.
7. Stop engine and reconnect mass air flow sensor harness connector.
8. Select Service $03 with GST. Check DTC P0102 is detected.
9. Select Service $04 with GST and erase the DTC P0102.
10. Start engine again and let it idle for at least 5 minutes.
11. Select Service $07 with GST. The 1st trip DTC P0171 or P0174 should be detected at this stage, if a malfunction exists. If so, go to [P0171, P0174 Fuel Injection System Function].
NOTE: If 1st trip DTC is not detected during above procedure, performing the following procedure is advised.
a. Turn ignition switch OFF and wait at least 10 seconds.
b. Start engine.
c. Maintain the following conditions for at least 10 consecutive minutes. Hold the accelerator pedal as steady as possible.
VHCL SPEED SE 50 - 120 km/h (31 - 75 mph)
CAUTION: Always drive vehicle at a safe speed.
12. If it is difficult to start engine at step 8, the fuel injection system has a malfunction.
13. Crank engine while depressing accelerator pedal. If engine starts, go to [P0171, P0174 Fuel Injection System Function].
If engine does not start, check exhaust and intake air leak visually.
NOTE: When depressing accelerator pedal three-fourths (3/4) or more, the control system does not start the engine. Do not depress accelerator pedal too much.
Diagnosis Procedure
Step 1-2:
