P0411 Code on Equinox and Terrain

P0411 Code on Chevrolet Equinox and GMC Terrain: Causes, Symptoms, and Solutions

The P0411 code is a common diagnostic trouble code on a Chevrolet Equinox and GMC Terrain. This article will delve into the specifics of this code for these particular models, exploring its meaning, causes, symptoms, and potential solutions. Whether you’re a DIY mechanic or simply want to understand what’s happening with your vehicle, this comprehensive guide will provide valuable insights into the P0411 code.

What Does the P0411 Code Mean?

The P0411 code stands for “Secondary Air Injection System Incorrect Flow Detected.” This code is related to the secondary air injection system. On the Chevrolet Equinox and GMC Terrain, this system is designed to reduce emissions by injecting fresh air into the exhaust stream to help burn off excess fuel and reduce pollutants.

When the vehicle’s computer detects that the secondary air injection system is not functioning correctly, it triggers the P0411 code. This could mean that either too much or too little air is flowing through the system compared to what the computer expects.

The Most Common Causes of the P0411 Code in Equinox and Terrain Models

Several issues can trigger the P0411 code in Chevrolet Equinox and GMC Terrain vehicles:

Faulty Air Injection Pump: The most common cause is a failure of the air injection pump itself. This pump is responsible for pushing fresh air into the exhaust system.
Damaged or Clogged Air Injection Lines: The lines that carry air from the pump to the exhaust can become clogged with debris or develop leaks over time.
Malfunctioning Air Injection Control Valve: This valve regulates when air is injected into the exhaust system. If it sticks or fails, it can trigger the P0411 code.
Electrical Issues: Problems with the wiring, connectors, or fuses related to the secondary air injection system can cause this code.
Failed Check Valve: This one-way valve prevents exhaust gases from flowing back into the air injection system. If it fails, it can damage other components and trigger the code.
PCM Issues: In rare cases, the Powertrain Control Module (PCM) itself may be faulty, misinterpreting signals from the air injection system.

Diagnose and fix Equinox and TerrainP0411

P0411: Secondary Air Injection System Incorrect Air Flow Detected

Diagnostic steps:

• Visual Inspection— Examine the air injection pump, lines, and electrical connections for obvious signs of damage or wear.
• Listen for the Pump— With the engine cold, start it and listen for the air injection pump. It should run for about 30 seconds after a cold start.
• Check Fuses and Relays— Inspect the fuses and relays associated with the secondary air injection system.
• Smoke Test— A smoke test can help identify leaks in the air injection lines.

Electrical and operational tests

1: Using a scan tool with live data, monitor the Air Injection Reaction (AIR) solenoid sensor data. There are two voltages to monitor: 1-2 and 3-4. When the AIR solenoid is off, look for voltages between 2.5-2.7 volts.

2: Use the bi-direction scan tool to activate the AIR solenoid; voltage should rise to 3.3 volts on both sensors.

3: Start the AIR pump using the scan tool or using jumper wires and monitor voltages. They should be around 2.9-volts. This represents a working pump with no restrictions on the cylinder head.

3: If you don’t see voltage in step one, check the solenoid relay on the left strut tower, fuse, or wiring harness.

4: If the voltages don’t change when you activate the pump, check for restrictions in the cylinder head.

How the AIR system works

The secondary air injection system is used during cold starts to add oxygen to the exhaust to help burn off excess hydrocarbons introduced into the exhaust due to the cold-rich mixture needed to start cold engines.

The system uses an electric air pump to force fresh air into the exhaust stream get the catalytic converter up to temperature faster.

The system also uses a pressure sensor and shutoff/check valve. The pressure sensor monitors back pressure. The shutoff/check valve opens the passage between the pump and the exhaust, and the check valve prevents exhaust gas from flowing backward into the pump.

The AIR solenoids are normally closed. When the AIR solenoids are energized, the valves open and air passes into the exhaust system. The AIR air pressure sensors operate similar to a Manifold Absolute Pressure Sensor (MAP) with different values.

Causes of Equinox and Terrain P0411

Buildup in the tube running from the shutoff valve to the cylinder head/exhaust.

GM service bulletin 18-NA-061 on P0411

GM UPPER ENGINE AND FUEL INJECTOR CLEANER

GM has issued a service bulletin 18-NA-061 on P0411. GM has determined that the P0411 condition can also be caused by moisture and/or ice build up in the Secondary Air Injection system in cold climate areas.

This condition may also be caused by a by-product of using inferior fuel, creating restriction in the SAI ports in the cylinder head causing higher than expected SAI operation pressure.

If you live in a cold climate, check for signs of ice or rust in the SAI components.

GM recommends using GM UPPER ENGINE AND FUEL INJECTOR CLEANER to remove any carbon deposits.

© , 2022 Rick Muscoplat