AutoCodes – Buick – P0412 Buick

P0412 Buick Code - Secondary Air Injection Solenoid Relay Control Circuit

Quick Answer

The Powertrain Control Module (PCM) controls the relay by grounding the control circuit via an internal switch called a driver. 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 Buick indicates Secondary Air Injection Solenoid Relay Control Circuit.
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 5,521

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
Comments
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Code P0412 Buick Description

The Powertrain Control Module (PCM) controls the relay by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which the PCM monitors. When the PCM commands a component ON, the voltage of the control circuit should be low (near 0 volts). When the PCM commands the control circuit to a component OFF, the voltage potential of the circuit should be high (near the battery voltage).
The relay controls the high current flow to the AIR injection pump integral bypass valve. This allows the PCM driver to only have to control the relatively low current used by the relay.

OBDII Code P0412 Buick - Secondary Air Injection Solenoid Relay Control Circuit - AutoCodes.com — P0412 Buick Code - Secondary Air Injection Solenoid Relay Control Circuit

What does this mean?

What are the Possible Causes of the DTC P0412 Buick?

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 Buick?

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 Buick 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.