P0491

P0491 - Secondary Air Injection System: Bank 1

P0491 - Secondary Air Injection System: Bank 1: Insufficient Flow

Possible Symptoms

• Malfunction Indicator Light (MIL) active

Possible Causes

• Fuse or relay for Secondary Air Injection Pump faulty
• Hose(s)/Piping between Secondary Air Injection Pump and Combi (Secondary Air Injection) Valve leaking
• Secondary Air Injection Solenoid(s) faulty
• Secondary Air Injection Pressure Sensor faulty
• Combi Valve(s) faulty
• Secondary Air Injection ports in the cylinder head(s) plugged with carbon See Special Notes

Possible Solutions

• Check fuse and relay for Secondary Air Injection Pump system.
• Check hose(s)/Piping between Secondary Air Injection Pump and Combi Valve
• Check Secondary Air Injection Solenoid(s)
• Check Secondary Air Injection Pressure Sensor
• Check Combi Valve(s)
• Clean Secondary Air Injection ports in the cylinder head(s) if obstructed with carbon See Special Notes

Special Notes

• When found in the following NAR (North American Market) Audi models listed below check to see if TPI 2033001 is applicable:

• Audi TPI 2033001 pertains to P0491 and P0492 stored at same time on the following vehicles with more than 15,000 miles:
  • 2010+ S4 and S5 with CCBA 3.0L
  • 2008+ A5, 2009+ A4, 2011 A6 with CALA 3.2L
  • 2009-2011 A6 CCAA 3.0L
  • 2012 A6/A7 CGXB 3.0L
  • 2013+A6/A7 CTUA 3.0L
  • 2009+ Q5 CALB 3.2L
  • 2011+ Q7 CJWE, CJWC, CJWB 3.0L