Yes, a clogged air filter can cause issues with the fuel trims on a vehicle and cause codes, but there’s something you may not be thinking about when you’re replacing one of these filters: the secondary air injection.
First of all, inspect the housing for the filter. Make sure there’s no cracks or any areas where unfiltered air can make its way into the engine. It could possibly contaminate the mass airflow sensor and then also the oxygen sensor itself.
But there is another emission system that uses that housing: the secondary air injection system. These systems use the mass airflow sensor when the pump is turned on for the secondary air injection to make sure it is flowing. That way, it can hopefully complete the monitor on the vehicle. But some vehicles have taken this tool to another level. BMW, Audi and other manufacturers are actually using a tiny mass airflow sensor for the secondary air injection system.
You may first notice this when you see a grams per second on your scan tool when you’re trying to diagnose one of these codes. So it is important that that tubing, the mass airflow sensor and the housing itself have integrity to be able to measure when the pump comes on. If it doesn’t, it’s going to set a code.
For more, watch the video above.
This video is presented by Auto Value and Bumper to Bumper.
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