Secondary Air Injection System, Bank 1 - Below Limit

P0491

Secondary Air Injection System, Bank 1 - Below Limit

Diagnosis conditions
- Intake air temperature 4.5 - 60 degree C
- Engine temperature 4.5 - 102 degree C
- Mass air flow 36 - 150 kg/h
- Engine starting temperature less than 42 degree C
- Altitude correction factor greater than 0.75
- Oxygen sensors 1 and 2 ahead of TWC are ready for operation
- The secondary air injection pump is switched on
- Diagnosis has not yet taken place during this cycle

Possible fault cause
- Secondary air injection pump is not triggered
- Secondary air injection pump does not work
- Air supply lines restricted
- Electric change-over valve does not function
- Air change-over valve does not function
- Vacuum system leaking

Affected terminals
III/11 and III/14

Diagnosis/Troubleshooting

NOTE: Secondary air diagnosis can be activated with the Porsche System Tester 2 in the "Short test" menu.

Work Instruction 1 - 4:

Work Instruction 5 - 6: