Fix Your 1.8T Secondary Air System — Before It Becomes a Bigger Problem.

A cracked or collapsed secondary air pipe on your MK4 1.8T will trigger a P0411 or P0491 fault code and keep your check engine light on. It's one of the most common failure points on the 1.8T engine — and one of the easiest to fix yourself.

What You're Getting

• Secondary air injection pipe for MK4 platform 1.8T engines
• Part number: BL0133817
• Direct OEM-spec replacement — plug and play, no modifications needed
• Restores proper secondary air flow to clear codes and pass emissions

Fits

• VW Golf MK4 1.8T
• VW Jetta MK4 1.8T
• VW GTI MK4 1.8T
• Confirm fitment by part number before ordering

Why Replace It?

The secondary air system on the 1.8T is notorious for cracking hoses and pipes as they age. A failed pipe means your engine can't complete its cold-start emissions cycle, leading to fault codes, failed e-tests, and rough cold starts. This is a straightforward swap — typically done in under an hour with basic tools.

Clear the code. Pass the test. Order yours today.