How serious is an emission control system code?

Most emission codes are moderate in severity. While they may not immediately affect drivability, they increase harmful exhaust emissions and should be repaired to maintain vehicle compliance and performance.

Can I fix emission codes myself?

Some emission issues like loose hoses or simple valve replacements can be DIY repairs. However, diagnosing the root cause often requires specialized equipment, so a professional diagnosis is recommended.

P0416

Secondary Air Injection System Switching Valve "B" Circuit Open

Moderateemission

Overview

The P0416 code indicates the PCM has identified a secondary air injection system switching valve "b" circuit open issue. This code is associated with the vehicle's emission control systems designed to reduce harmful exhaust pollutants. A malfunction in these systems can increase vehicle emissions beyond acceptable limits and will likely cause a failed emissions inspection.

Symptoms

Reduced engine performance
Unusual exhaust smell
Failed emissions test
Hissing or sucking sound from engine bay

Common Causes

Faulty secondary air injection pump
Failed check valve in air injection system
Failed relay in the air injection system
Damaged or disconnected air injection hoses

Diagnosis Steps

1Connect an OBD-II scanner and read all stored trouble codes and freeze frame data
2Inspect the secondary air injection pump for proper operation
3Check all hoses and pipes in the air injection system for damage or leaks
4Test the switching valve solenoid and relay with a multimeter
5Verify airflow through the system using a flow meter if available

Estimated Repair Cost

$200 — $700

Cost varies by vehicle, location, and repair shop. Includes parts and labor.

Commonly Affected Vehicles

Subaru OutbackVolkswagen PassatHonda CR-VFord Focus

Related Codes

P0410 P0411 P0430

More Emission Codes

P0410Secondary Air Injection System Malfunction

Moderate

P0411Secondary Air Injection System Incorrect Flow Detected

Moderate

P0412Secondary Air Injection System Switching Valve "A" Circuit

Moderate

P0413Secondary Air Injection System Switching Valve "A" Circuit Open

Moderate

P0414Secondary Air Injection System Switching Valve "A" Circuit Shorted

Moderate

P0415Secondary Air Injection System Switching Valve "B" Circuit

Moderate

Frequently Asked Questions

Yes, any illuminated Check Engine Light will result in a failed emissions inspection. The emission system issue must be repaired and the code cleared before the vehicle can pass.