P0491

Q: What does OBD2 code P0491 mean?

P0491 means: Secondary Air Injection System Insufficient Flow Bank 1. Learn about OBDtrouble code P0491: Secondary Air Injection System Insufficient Flow Bank 1. Find causes, symptoms, and step-by-step repair solutions.

Secondary Air Injection System Insufficient Flow Bank 1

Learn about OBDtrouble code P0491: Secondary Air Injection System Insufficient Flow Bank 1. Find causes, symptoms, and step-by-step repair solutions.

SeverityMinor

CategoryEmissions

Est. Repair Cost$200–$900

Code TypePowertrain

DIY RepairProfessional

⚡ Common Causes

›Failed AIR pump
›Clogged check valve
›Failed AIR solenoid
›Vacuum line leak

⚠️ Symptoms

›Check engine light
›Emissions test failure

✅ How to Fix — Step by Step

Step 1:Test AIR pump
Step 2:Inspect check valves
Step 3:Test solenoid
Step 4:Repair vacuum lines

Repair Cost Estimate

Full Repair Estimate

$200–$900

DIY Possible?

PRO

Severity

Minor

Frequently Asked Questions

What does OBD2 code P0491 mean?+

P0491 stands for Secondary Air Injection System Insufficient Flow Bank 1. Learn about OBDtrouble code P0491: Secondary Air Injection System Insufficient Flow Bank 1. Find causes, symptoms, and step-by-step repair solutions.

What causes code P0491?+

Failed AIR pump; Clogged check valve; Failed AIR solenoid; Vacuum line leak

How do I fix code P0491?+

Test AIR pump; Inspect check valves; Test solenoid; Repair vacuum lines

How much does it cost to fix P0491?+

Estimated repair cost for P0491 is $200–$900.

Is P0491 DIY-friendly?+

P0491 typically requires professional equipment and a qualified mechanic.