AutoCodes – Mercedes-Benz – P0412 Mercedes-Benz

P0412 Mercedes-Benz Code - Secondary Air Injection System Switching Valve '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: P0412 Mercedes-Benz indicates Secondary Air Injection System Switching Valve '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 12,469

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 Jun 14, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0412 Mercedes-Benz 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 P0412 Mercedes-Benz - Secondary Air Injection System Switching Valve 'A' Circuit Malfunction - AutoCodes.com — P0412 Mercedes-Benz Code - Secondary Air Injection System Switching Valve 'A' Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P0412 Mercedes-Benz?

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

How to Fix the DTC P0412 Mercedes-Benz?

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 P0412 Mercedes-Benz 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.

Need more information about the P0412 Mercedes-Benz code?

Need more information on how to fix the P0412 Mercedes-Benz code? Get Access to Factory Service Manuals

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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 P0412 Mercedes-Benz Code

1. What are the common symptoms of OBDII code P0412 in a Mercedes-Benz?

The common symptoms of P0412 include the check engine light illuminating on the dashboard, rough idling, decreased engine performance, and potential exhaust system noises.

2. What causes the OBDII code P0412 in a Mercedes-Benz?

The P0412 code is typically triggered by a malfunction in the Secondary Air Injection System Switching Valve 'A', which can be caused by a faulty valve, damaged wiring, or a poor electrical connection.

3. How serious is the OBDII code P0412 in a Mercedes-Benz?

While the P0412 code may not cause immediate drivability issues, it can lead to increased emissions and potential damage to the catalytic converter over time if left unresolved.

4. Can I continue driving my Mercedes-Benz with the OBDII code P0412 present?

It is generally not recommended to continue driving with the P0412 code active, as it can negatively impact engine performance and emissions. It is best to address the issue as soon as possible.

5. How can I diagnose the OBDII code P0412 in my Mercedes-Benz?

Diagnosing the P0412 code typically involves using an OBDII scanner to retrieve the fault code, visually inspecting the Secondary Air Injection System components, and testing the Switching Valve 'A' circuit for proper functionality.

6. What are some repair tips for fixing the OBDII code P0412 in a Mercedes-Benz?

Repair tips for addressing the P0412 code may include checking and replacing the Secondary Air Injection System Switching Valve 'A', inspecting and repairing any damaged wiring or connectors, and clearing the fault code with an OBDII scanner.

7. Can I fix the OBDII code P0412 in my Mercedes-Benz myself?

Depending on your level of automotive experience, you may be able to address the P0412 code yourself by following repair guides, replacing components, and clearing the fault code. However, professional diagnostics and repairs may be necessary in some cases.

8. How much does it typically cost to repair the OBDII code P0412 in a Mercedes-Benz?

The cost of repairing the P0412 code can vary depending on the specific issue causing the fault, the labor rates of the repair shop, and the cost of any replacement parts needed. It is recommended to obtain quotes from multiple sources for an accurate estimate.

9. Are there any preventive measures to avoid the OBDII code P0412 in a Mercedes-Benz?

Regular maintenance and inspections of the Secondary Air Injection System components, including the Switching Valve 'A', can help prevent issues that may trigger the P0412 code. Keeping the vehicle well-maintained can reduce the likelihood of this fault occurring.

10. How long does it typically take to repair the OBDII code P0412 in a Mercedes-Benz?

The repair time for the P0412 code can vary depending on the complexity of the issue and the availability of replacement parts. In some cases, the repair may be completed within a few hours, while more extensive repairs could take longer.