Fault code P1434 – a step-by-step guide to diagnosing and fixing it

Error code P1434 is displayed and the check engine light is on - what does this mean?

The OBD/EOBD system has detected an error in the secondary air injection area, specifically in the monitoring of the air flow or valve control. This manufacturer-specific DTC P1434 mainly affects the secondary air system, which is used to reduce emissions during the warm-up phase of the engine.

What can cause this error code?

• Defective secondary air pump
• Blocked or damaged secondary air valve
• Defective secondary air relay
• Blocked or leaking secondary air lines
• Faulty wiring to the secondary air system
• Defective mass air flow sensor
• Clogged air filter in the secondary air system
• Corroded or loose plug connections
• Defective control unit software

What symptoms occur in parallel with fault code P1434?

• Increased emission values: Poorer emission values during the emissions test
• Uneven idling: Engine runs unevenly at idle speed
• Poor cold start performance: Delayed starting when the engine is cold
• Increased fuel consumption: Measurably higher consumption, especially on short journeys
• Check engine light: Permanently lit or flashing warning light
• Abnormal engine noises: Unusual noises during the warm-up phase

How can the problem with error code P1434 be rectified?

• The repair requires a systematic diagnosis of the secondary air system and appropriate measures.
• Check and replace the secondary air pump: Test pump for proper function, replace completely if defective and check wiring
• Clean or replace secondary air valve: Dismantle valve, clean thoroughly or replace with new part if irreparably damaged
• Check relays and fuses: Replace secondary air relay, check associated fuses and measure power supply
• Inspect air lines and hoses: Check all connections for leaks, replace damaged hoses and tighten connections
• Repair wiring and plug connections: Inspect wiring harness for breaks, clean corroded contacts and replace defective wiring
• Clean or replace the mass air flow sensor: Remove LMM, clean with special cleaner or replace with new part if defective
• Carry out a software update: Update the control unit to the latest software version and carry out the basic settings again