Fault code P0411 – a step-by-step guide to diagnosing and fixing it

Error code P0411 is displayed and the check engine light is on - what does this mean?

The OBD/EOBD system has detected a fault in the secondary air system, or more precisely an incorrect air flow. This DTC P0411 indicates that the secondary air system is not working properly and the expected amount of air is not being fed into the exhaust system. This error code may have slightly different definitions for different manufacturers, but it generally refers to problems with the secondary air injection.

What causes can this error code have?

• Defective secondary air pump
• Blocked or damaged secondary air hoses
• Defective secondary air switching valve
• Clogged air filter of the secondary air pump
• Damaged non-return valves in the secondary air system
• Loose or corroded plug connections
• Clogged injection valves in the exhaust manifold
• Defective wiring to the secondary air system
• Leaks in the intake system

What symptoms occur in parallel with fault code P0411?

• Engine performance: Reduced engine power and rough idling
• Exhaust emissions: Increased pollutant values and worsened exhaust gas values
• Noises: Unusual noises from the secondary air pump during cold start
• Fuel consumption: Increased fuel consumption due to inefficient combustion
• Starting behavior: Difficult cold starts and prolonged warm-up phase
• Exhaust odor: Increased exhaust odor due to incomplete post-combustion

How can the problem with error code P0411 be rectified?

• The repair of error code P0411 requires a systematic check of the secondary air system and its components.
• Replace the secondary air pump completely if it is defective or makes unusual noises
• Check all hoses and lines of the secondary air system for cracks, blockages or leaks and replace if necessary
• Test the secondary air switching valve and replace with a new valve if it is not working properly
• Clean the air filter of the secondary air pump or replace it if it is clogged
• Check non-return valves in the system and replace defective valves
• Check all electrical connections and plug connections for corrosion and clean them
• Measure the wiring to the secondary air system with a multimeter and repair damaged cables
• Check injection valves in the exhaust manifold for blockages and clean if necessary