Fault code P1408 – a step-by-step guide to diagnosing and fixing it

Error code P1408 is displayed and the check engine light is on - what does this mean?

The OBD system has detected a fault in the secondary air system, specifically a short circuit or an interruption in the secondary air pump circuit. This manufacturer-specific DTC P1408 mainly occurs in Volkswagen, Audi, Seat and Skoda vehicles and indicates electrical problems in the secondary air injection system.

What causes can this error code have?

• Defective secondary air pump
• Damaged wiring to the secondary air system
• Corroded or loose plug connections
• Defective secondary air valve
• Blown fuse in the secondary air circuit
• Faulty engine control unit (ECU)
• Oxidized contacts in the relay box
• Damaged air lines to the secondary air system

What symptoms occur in parallel with fault code P1408?

• Starting problems: The vehicle requires longer starting times, especially when the engine is cold
• Increased emissions: Poorer exhaust emissions and possible failure at the main inspection
• Uneven idling: Engine runs unevenly at idle speed
• Poor cold running performance: Delayed warm-up phase and jerky engine running
• Increased fuel consumption: Noticeably higher consumption due to inefficient combustion

How can the problem with error code P1408 be rectified?

• The repair requires a systematic diagnosis of the secondary air system and the associated electrical system.
• Check fuses and relays: Check all fuses in the secondary air circuit and replace defective components, replace relays and test function
• Inspect wiring: Complete check of all cables to the secondary air pump for damage, short circuits or breaks, repair or replace damaged cables
• Clean plug connections: Disconnect all electrical connections on the secondary air system, clean with contact spray and reconnect firmly
• Replace secondary air pump: If pump is defective, carry out complete replacement, install new pump and check function
• Replace secondary air valve: Remove valve, check for continuity and replace with new original part if defective
• Check engine control unit: Carry out ECU diagnostics and update software or replace control unit if necessary