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 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 rich), 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
P0172 | Fuel injection system too rich (bank 1) |

- Fuel injection system does not operate properly.
- The amount of mixture ratio compensation is too large. (The mixture ratio is too rich.)

- A/F sensor 1
- Fuel injector
- Exhaust gas leaks
- Incorrect fuel pressure
- Mass air flow sensor

P0175 | Fuel injection system too rich (bank 2)

DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test.

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.

>>GO TO 2.
2.PERFORM DTC CONFIRMATION PROCEDURE-I

1. Clear the mixture ratio self-learning value. Refer to Special Repair Requirement (GT-R certified NISSAN dealer).
2. Start engine.

Is it difficult to start engine?
YES>>GO TO 3.
NO>>GO TO 4.
3.RESTART ENGINE
If it is difficult to start engine, the fuel injection system has a malfunction, too.
Crank engine while depressing accelerator pedal.
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.
Does engine start?
YES>>Go to Diagnosis Procedure (GT-R certified NISSAN dealer).
NO>>Remove spark plugs and check for fouling, etc.
4.PERFORM DTC CONFIRMATION PROCEDURE-II

1. Keep engine idle for at least 5 minutes.
2. Check 1st trip DTC.

Is 1st trip DTC detected?
YES>>Go to Diagnosis Procedure (GT-R certified NISSAN dealer).
NO>>GO TO 5.
5.PERFORM DTC CONFIRMATION PROCEDURE-III

1. Turn ignition switch OFF and wait at least 10 seconds.
2. Start engine.
3. 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 safe speed.
4. Check 1st trip DTC.

Is 1st trip DTC detected?
YES>>Go to Diagnosis Procedure (GT-R certified NISSAN dealer).
NO>>INSPECTION END