AutoCodes – Volkswagen – P0491 Volkswagen

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

Quick Answer

The AIR system refers to an emissions control system used by some vehicle manufacturers. Common causes include Intake leak, Damaged AIR system components, Faulty AIR Solenoid Valve. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means: P0491 Volkswagen indicates Secondary Air Injection System Insufficient Flow Bank 1.
Common causes: Common causes include Intake leak, Damaged AIR system components, Faulty AIR Solenoid Valve.
Severity: Low - monitor the vehicle and repair when practical.
Can I drive?: The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

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Code Popularity 29,012

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 12, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0491 Volkswagen Description

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.

OBDII Code P0491 Volkswagen - Secondary Air Injection System Insufficient Flow Bank 1 - AutoCodes.com — P0491 Volkswagen Code - Secondary Air Injection System Insufficient Flow Bank 1

What does this mean?

What are the Possible Causes of the DTC P0491 Volkswagen?

Intake leak
Damaged AIR system components
Faulty AIR Solenoid Valve
Faulty AIR system relay

How to Fix the DTC P0491 Volkswagen?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0491 Volkswagen code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0491 Volkswagen Code

1. What are the common symptoms of OBDII code P0491 in a Volkswagen related to the Secondary Air Injection System Insufficient Flow Bank 1?

- Common symptoms include the illumination of the check engine light, rough idling, decreased engine performance, and potential emissions issues.

2. What are the possible causes of OBDII code P0491 in a Volkswagen indicating an issue with the Secondary Air Injection System?

- Causes may include a faulty secondary air injection pump, a clogged or leaking air injection system, damaged vacuum lines, or a malfunctioning air flow sensor.

3. How can I diagnose the OBDII code P0491 on my Volkswagen with a suspected Secondary Air Injection System problem?

- Diagnosis involves using an OBDII scanner to retrieve the specific code, conducting a visual inspection of the air injection system components, and performing tests on the pump, valves, and associated wiring.

4. What are some repair tips for addressing OBDII code P0491 in a Volkswagen due to Secondary Air Injection System Insufficient Flow Bank 1?

- Repair may involve replacing the secondary air injection pump, cleaning or replacing clogged air injection system components, repairing damaged vacuum lines, or addressing faulty sensors.

5. Can I drive my Volkswagen with OBDII code P0491 related to the Secondary Air Injection System issue?

- It is generally not recommended to drive the vehicle with this code as it can lead to reduced engine performance, increased emissions, and potential long-term damage to the engine components.

6. How much does it typically cost to repair OBDII code P0491 on a Volkswagen caused by a problem in the Secondary Air Injection System?

- The cost of repair can vary depending on the specific issue, but it may range from a few hundred to over a thousand dollars, including parts and labor.

7. Are there any preventative maintenance steps I can take to avoid encountering OBDII code P0491 in my Volkswagen?

- Regular maintenance, such as inspecting and cleaning the air injection system components, checking for vacuum leaks, and replacing worn-out parts, can help prevent issues leading to this code.

8. Can a DIY enthusiast repair OBDII code P0491 on a Volkswagen related to the Secondary Air Injection System, or is it best left to professionals?

- While some simple repairs, like replacing vacuum lines, can be done by DIYers, dealing with complex components like the air injection pump may require professional expertise to ensure proper diagnosis and repair.

9. Will resetting the check engine light temporarily resolve OBDII code P0491 in a Volkswagen, or is it necessary to address the underlying issue?

- Resetting the check engine light may temporarily turn it off, but the code will likely reappear if the underlying problem with the Secondary Air Injection System is not addressed.

10. How long does it typically take for a mechanic to diagnose and repair OBDII code P0491 on a Volkswagen related to the Secondary Air Injection System?

- The time for diagnosis and repair can vary based on the complexity of the issue, but it may take a few hours to a day for a mechanic to properly diagnose and fix the problem.