P0491 OBD-II: Secondary Air Injection System Insufficient Flow
P0491 Severity
Will P0491 go away on its own?
Once the vehicle's onboard system no longer detects the issue, most codes will disappear on their own. If your vehicle still has this code, however, it should be properly diagnosed to avoid a more serious problem.
For a proper diagnosis, RepairPal Certified shops have the equipment, tools, and expertise.
Moderate severity codes might not threaten the vehicle's safety or functionality immediately, but you should still get it diagnosed within a reasonable time frame to keep your car running well.
What causes OBD-II fault code P0491?
The Secondary Air Injection System pumps outside fresh air into the Exhaust System during cold engine start up. This additional air helps burn up the highly rich exhaust emissions that are produced when the engine is warming up. The Secondary Air System typically has an Air Pump and some tubes or plumbing to route the air. The system also has a solenoid and Check Valve(s) to control the airflow. When the engine control module (PCM) detects a faulty with the Secondary Air Injection System, it will set code P0491.
Ask our experts about P0491.
RepairPal Car Genius™ is a free resource for vehicle owners seeking advice on maintenance, auto repair, shop inquiries, estimates, and finding a trustworthy repair shop in your area.
Call us at 877-913-1554
Available 9am – 6pm ET Monday through Friday
