AutoCodes – Audi – P0418 Audi

P0418 Audi Code - Secondary Air Injection System Relay 'A' Circuit Malfunction

Quick Answer

An air pump is used on the vehicle to lower tail pipe emissions on start-up. Common causes include Faulty Air Pump inoperative, Air bypass solenoid harness is open or shorted, Air bypass solenoid circuit poor electrical connection. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: P0418 Audi indicates Secondary Air Injection System Relay 'A' Circuit Malfunction.
Common causes: Common causes include Faulty Air Pump inoperative, Air bypass solenoid harness is open or shorted, Air bypass solenoid circuit poor electrical connection.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 9,700

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Apr 18, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0418 Audi Description

An air pump is used on the vehicle to lower tail pipe emissions on start-up. The Powertrain Control Module (PCM) grounds the Air pump relay control circuit which energizes the Air pump. The PCM also grounds the Air combination valve vacuum control solenoid circuit, which energizes the Air vacuum control solenoid. Vacuum is then applied to both Air combination valve diaphragms which opens the shut off valves. The PCM enables both circuits simultaneously when Air system operations id desired. When the AIR system is active, then Air pump forces fresh air into the exhaust stream in order to accelerate catalyst operation. The AIR combination valves replace the conventional check valves. When the AIR system is inactive the shut off valves prevent air flow in either direction.

OBDII Code P0418 Audi - Secondary Air Injection System Relay 'A' Circuit Malfunction - AutoCodes.com — P0418 Audi Code - Secondary Air Injection System Relay 'A' Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P0418 Audi?

Faulty Air Pump inoperative
Air bypass solenoid harness is open or shorted
Air bypass solenoid circuit poor electrical connection

How to Fix the DTC P0418 Audi?

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 P0418 Audi 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 P0418 Audi Code

1. What are common symptoms of OBDII code P0418 in an Audi related to the Secondary Air Injection System Relay 'A' Circuit Malfunction?

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

2. What could cause the OBDII code P0418 to trigger in an Audi?

- The code P0418 typically triggers in an Audi due to a faulty secondary air injection system relay, damaged wiring or connectors, or a malfunctioning secondary air injection pump.

3. How can I diagnose the Secondary Air Injection System Relay 'A' Circuit Malfunction in my Audi?

- Diagnose the issue by conducting a visual inspection of relay connections, checking for damaged wiring or connectors, and using a multimeter to test the relay's functionality.

4. Is it safe to continue driving my Audi with OBDII code P0418 related to the Secondary Air Injection System Relay 'A' Circuit Malfunction?

- It is generally not recommended to drive your Audi with this code as it may lead to poor engine performance and potential emissions issues. It's best to address the problem promptly.

5. Can I repair the Secondary Air Injection System Relay 'A' Circuit Malfunction in my Audi myself?

- If you have the necessary tools and automotive knowledge, you may be able to replace the faulty relay or repair damaged wiring yourself. However, seeking professional help is advisable for accurate diagnosis and repair.

6. How much does it typically cost to repair OBDII code P0418 in an Audi?

- The cost of repairing OBDII code P0418 can vary depending on the underlying issue. It may range from $100 to $500, including parts and labor.

7. Are there any preventive measures to avoid triggering code P0418 in an Audi?

- Regularly maintaining your Audi, including checking the secondary air injection system components during scheduled services, can help prevent issues that may trigger code P0418.

8. Can a faulty secondary air injection system relay affect the overall performance of my Audi?

- Yes, a faulty relay in the secondary air injection system can lead to decreased engine performance, rough idling, and potentially higher emissions levels in your Audi.

9. How urgent is it to address OBDII code P0418 in an Audi?

- It is advisable to address code P0418 promptly to prevent any further damage to the secondary air injection system and ensure optimal engine performance.

10. Will resetting the check engine light resolve OBDII code P0418 related to the Secondary Air Injection System Relay 'A' Circuit Malfunction?

- Simply resetting the check engine light will not fix the underlying issue causing code P0418. It's essential to diagnose and repair the problem to prevent the code from reoccurring.