P0411moderate severityPowertrain
Secondary Air Injection System Incorrect Flow Detected
on 2004 GMC Yukon 5.3L V8 Vortec · RWD
What this code means
The secondary air injection system is not providing the expected airflow.
Symptoms
- Check Engine Light
- Failed emissions test
Common causes
- Blocked AIR passages
- Stuck check valve
- Weak AIR pump
- Exhaust leak allowing backflow
Diagnostic steps
- Monitor O2 sensor during AIR pump activation (should go lean)
- Check AIR pump output
- Inspect check valve
- Check for blocked passages
Repair notes
Clear blockage or replace AIR pump/check valve.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1