DTC DETECTION 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 A/F sensor 1. The ECM calculates the necessary compensation to correct the offset between the actual and 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).

Sensor
Input signal to ECM
ECM function
Actuator
A/F sensor 1
Density of oxygen in exhaust gas
(Mixture ratio feedback signal)
Fuel injection control
Fuel injector


DTC No.
Trouble diagnosis name
DTC detecting condition
Possible cause
P0171
Fuel injection system too lean (bank 1)
  • Fuel injection system does not operate properly.
  • The amount of mixture ratio compensation is too large. (The mixture ratio is too lean.)
  • Intake air leaks
  • A/F sensor 1
  • Fuel injector
  • Exhaust gas leaks
  • Incorrect fuel pressure
  • Lack of fuel
  • Mass air flow sensor
  • Incorrect PCV hose connection
P0174
Fuel injection system too lean (bank 2)

 
 DTC CONFIRMATION PROCEDURE

 
 1.PRECONDITIONING
 
 2.PERFORM DTC CONFIRMATION PROCEDURE-I
 
 3.RESTART ENGINE
 
 4.PERFORM DTC CONFIRMATION PROCEDURE-II
 
 5.PERFORM DTC CONFIRMATION PROCEDURE-III