DTC DETECTION LOGIC When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the crankshaft position (CKP) sensor (POS) signal to vary, ECM can determine that a misfire is occurring.

Sensor | Input signal to ECM | ECM function
Crankshaft position sensor (POS) | Engine speed | On board diagnosis of misfire

The misfire detection logic consists of the following two conditions.

1.One Trip Detection Logic (Three Way Catalyst Damage) On the 1st trip that a misfire condition occurs that can damage the three way catalyst (TWC) due to overheating, the MIL will blink.When a misfire condition occurs, the ECM monitors the CKP sensor signal every 200 engine revolutions for a change.When the misfire condition decreases to a level that will not damage the TWC, the MIL will turn off.If another misfire condition occurs that can damage the TWC on a second trip, the MIL will blink.When the misfire condition decreases to a level that will not damage the TWC, the MIL will remain on.If another misfire condition occurs that can damage the TWC, the MIL will begin to blink again.

2.Two Trip Detection Logic (Exhaust quality deterioration)For misfire conditions that will not damage the TWC (but will affect vehicle emissions), the MIL will only light when the misfire is detected on a second trip. During this condition, the ECM monitors the CKP sensor signal every 1,000 engine revolutions.A misfire malfunction can be detected in any one cylinder or in multiple cylinders.

DTC No. | Trouble diagnosis name | DTC detecting condition | Possible cause
P0300 | Multiple cylinder misfires detected | Multiple cylinder misfire. |

- Improper spark plug
- Insufficient compression
- Incorrect fuel pressure
- The fuel injector circuit is open or shorted
- Fuel injector
- Intake air leak
- The ignition signal circuit is open or shorted
- Lack of fuel
- Signal plate
- A/F sensor 1
- Incorrect PCV hose connection

P0301 | No.1 cylinder misfire detected | No. 1 cylinder misfires.
P0302 | No. 2 cylinder misfire detected | No. 2 cylinder misfires.
P0303 | No. 3 cylinder misfire detected | No. 3 cylinder misfires.
P0304 | No. 4 cylinder misfire detected | No. 4 cylinder misfires.
P0305 | No. 5 cylinder misfire detected | No. 5 cylinder misfires.
P0306 | No. 6 cylinder misfire detected | No. 6 cylinder misfires.

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. 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. Restart engine and let it idle for about 15 minutes.
6. Check 1st trip DTC.

Is 1st trip DTC detected?
YES>>Go to Diagnosis Procedure (GT-R certified NISSAN dealer).
NO>>GO TO 3.
3.PERFORM DTC CONFIRMATION PROCEDURE-II

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.
4. Start engine and drive the vehicle under similar conditions to (1st trip) Freeze Frame Data for a certain time. Refer to the table below.Hold the accelerator pedal as steady as possible.Similar conditions to (1st trip) Freeze Frame Data mean that the following conditions should be satisfied at the same time.
   ■ CAUTION ■
   Always drive vehicle in safe manner according to traffic conditions and obey all traffic laws when driving.

   Engine speed | Engine speed in the freeze frame data ± 400 rpm
   Vehicle speed | Vehicle speed in the freeze frame data ± 10 km/h (6 MPH)
   Engine coolant temperature (T) condition | When the freeze frame data shows lower than 70 °C (158 °F), T should be lower than 70 °C (158 °F).
   When the freeze frame data shows higher than or equal to 70 °C (158 °F), T should be higher than or equal to 70 °C (158 °F).

   Driving time varies according to the engine speed in the freeze frame data.

   Engine speed | Time
   Around 1,000 rpm | Approximately 10 minutes
   Around 2,000 rpm | Approximately 5 minutes
   More than 3,000 rpm | Approximately 3.5 minutes

5. Check 1st trip DTC.

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