P0491
Secondary Air Injection System Insufficient Flow Bank 1
Generic code
Auxiliary Emissions Control
High severity
Hard repair
Free on OBD DashX
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What P0491 means
- The fault code P0491 indicates that there is a problem with the secondary air injection system in your vehicle.
Possible symptoms
- Illuminated check engine light
- Decreased engine performance and acceleration
- Engine may stall or run roughly
- Increased emissions output
Possible causes
- Failed air pump or air pump relay
- Clogged or blocked air lines
- Faulty vacuum hoses
- Failed check valve
- Malfunctioning oxygen sensor
- Faulty catalytic converter
Related parts
- Air Injector: Air is injected into the exhaust gases for better combustion of unburnt fuel and pollutants through air injectors. This allows for better exhaust emission. Problems lead to harmful emissions out of limit
Possible solutions
- Replace the air pump or air pump relay
- Clean or replace clogged or blocked air lines
- Check and replace faulty vacuum hoses
- Replace the check valve if necessary
- Check and replace the oxygen sensor if necessary
- Replace the catalytic converter if necessary
Free on OBD DashX
P0491 on OBD DashX
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