System Too Lean: What Does That Even Mean?

If you’ve ever installed a high-flow air intake — or run an oxygenated fuel such as E85 in a vehicle that isn’t intended to run it — you’ve bathed in the glow of an Amber Check Engine light emanating from your dashboard. What exactly causes a System Too Lean condition, is System Too Lean harmful and can you fix a System Too Lean code? HumbleMechanic, the Internet’s favorite Volkswagen technician, has some answers in a technical video that helps to remove the mystery from one of the most common OBDII code faults.

What can trigger your check engine light for a System Too Lean code? Excess air can possibly be delivered to your engine if the car’s stock intake manifold tube is ripped or torn past the filter. This can allow unfiltered air to enter into the throttle body and ultimately the combustion chamber, which can potentially damage the engine.

Inspect your intake tube for tears, rips or damage, paying special attention to the underside of the pipe. If your intake tube is torn, you can search Pull-A-Part inventory for a matching vehicle near you and replace the part to prevent damage and extinguish the System Lean fault code for good.