2020 Subaru Forester P code Page 68

Time Needed for Diagnosis: 200 engine revs.

Malfunction Indicator Light Illumination: Illuminates as soon as a malfunction occurs.

Normality Judgment

Time Needed for Diagnosis: 200 engine revs.

P0304

DTC P0304 CYLINDER 4 MISFIRE DETECTED

1. OUTLINE OF DIAGNOSIS

Detect the presence of misfire occurrence. (Revolution fluctuation method) Monitoring Misfire which influences exhaust deterioration (1.5

times of FTP) and catalyst damage is made obligatory by the law. Misfire affecting these two has two patterns below. :

- Intermittent misfire (The same cylinder misfires in random, or different cylinders misfire in random.): FTP 1.5 times misfire

- Every time misfire (The same cylinder misfires every time.): FTP 1.5 times misfire, Catalyst damage misfire

The following detecting methods are adopted for these detection.

1. Intermittent misfire: FTP 1.5 times misfire

- 180锟斤拷 Interval Difference Method (MT: 1,800 rpm or less; AT: None)

- 360锟斤拷 Interval Difference Method (whole range)

- 720锟斤拷 Interval Difference Method (3,000 rpm or more)

2. Misfire every time: FTP 1.5 times misfire, Catalyst damage misfire

- 360锟斤拷 Interval Difference Method