Engine-Codes - Audi - P0491 Audi

P0491 Audi Code - Secondary Air Injection System Insufficient Flow Bank 1

- Code Popularity: 19,150 Views
- Repair Importance Level: 2/3
- Repair Difficulty Level: 2/3
Table of contents
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What are the Possible Causes of the DTC P0491 Audi?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Intake leak
  • Damaged AIR system components
  • Faulty AIR Solenoid Valve
  • Faulty AIR system relay
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How to Fix the DTC P0491 Audi?

Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

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What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the P0491 Audi code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

What Does the P0491 Audi Code Mean?

The AIR system refers to an emissions control system used by some vehicle manufacturers. It is often called Secondary Air Injection, because air, more specifically oxygen, is injected into the exhaust manifold after startup. Vehicles start on a comparatively rich mixture to allow for smoother running conditions. However, this has a large impact on exhaust gas emissions. A notable increase in hydrocarbon (HC) and carbon monoxide (CO) emissions are found under these rich start conditions. By injecting air into the exhaust manifold the CO and HC can be oxidized. This reaction increases the temperature within the exhaust and the exhaust gas after-treatment system i.e. catalytic converter can begin working earlier due to meeting its light-off temperature.
The system consists of an air pump, a one-way check valve and associated pipework. The system operates for a predetermined time after startup. Normally this duration is approximately three minutes, when cold.

P0491 Audi Code - Secondary Air Injection System Insufficient Flow Bank 1

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