On Board Diagnosis Logic
WARNING: This page is about a different car, the 2005 Nissan Titan. However, it is still accessible from the selected car via links, so may be relevant.
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 sensors 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 rich.), the ECM judges the condition as the fuel injection system malfunction and lights up the MIL (2 trip detection logic).
ON BOARD DIAGNOSTIC (OBD) CHART
| 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 |
DIAGNOSTIC PROCEDURE CHART
| DTC No. | Trouble diagnosis name | DTC detecting condition | Possible cause |
|---|---|---|---|
| P0172 0172 (Bank 1) | Fuel injection system too rich |
|
|
| P0175 0175 (Bank 2) |