AutoCodes – Toyota – P0412 Toyota

P0412 Toyota 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 Toyota 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 34,752

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 Toyota 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 Toyota - Secondary Air Injection System Switching Valve 'A' Circuit Malfunction - AutoCodes.com — P0412 Toyota Code - Secondary Air Injection System Switching Valve 'A' Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P0412 Toyota?

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 Toyota?

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 Toyota 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 P0412 Toyota Code

1. What are the common symptoms of OBDII code P0412 in a Toyota?

Symptoms may include rough idling, engine hesitation, decreased fuel efficiency, and the illumination of the Check Engine Light.

2. What does the OBDII code P0412 for a Toyota indicate?

This code indicates a malfunction in the Secondary Air Injection System Switching Valve 'A' circuit.

3. What are the possible causes of OBDII code P0412 in a Toyota?

Possible causes include a faulty switching valve, damaged wiring or connectors, a blown fuse, or a problem with the ECM.

4. How serious is OBDII code P0412 in a Toyota?

While the vehicle may still be operable with this code, it is important to address the issue promptly to prevent potential damage to the catalytic converter and ensure proper emissions control.

5. How can I diagnose OBDII code P0412 in my Toyota?

Diagnosis involves inspecting the switching valve, checking the wiring for continuity, testing the fuse, and using a scan tool to monitor the system operation.

6. Can I continue driving my Toyota with OBDII code P0412?

It is generally safe to drive the vehicle for a short period with this code, but it is recommended to have the issue diagnosed and repaired as soon as possible to avoid further complications.

7. How can I repair OBDII code P0412 in my Toyota?

Repair may involve replacing the switching valve, repairing damaged wiring, replacing a blown fuse, or reprogramming the ECM.

8. Will resetting the Check Engine Light resolve OBDII code P0412 in my Toyota?

Simply resetting the light will not fix the underlying issue causing the code. It is important to diagnose and repair the problem to prevent it from recurring.

9. Can a DIY enthusiast fix OBDII code P0412 in a Toyota?

Depending on their skill level, a DIY enthusiast may be able to address this issue by following repair guides and utilizing the necessary tools and equipment.

10. How much does it typically cost to repair OBDII code P0412 in a Toyota?

The cost of repair can vary depending on the specific cause of the issue, but it may range from $100 to $500 or more, including parts and labor.