# Check engine after new air filter **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [February 4, 2008, 2:00am UTC](https://community.cartalk.com/t/check-engine-after-new-air-filter/10221 "2008-02-04T02:00:48Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![glennallison](https://avatars.discourse-cdn.com/v4/letter/g/8797f3/32.png) [@glennallison](https://community.cartalk.com/u/glennallison)\ **Post date:** [February 4, 2008, 2:00am UTC](https://community.cartalk.com/t/check-engine-after-new-air-filter/10221/1 "2008-02-04T02:00:48Z")
2001 Rav4 is giving check engine (both banks running lean) after putting in new air filter. Absolutely no codes prior to this simple act, but now fails smog test. Does this make any sense? ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [February 4, 2008, 2:20am UTC](https://community.cartalk.com/t/check-engine-after-new-air-filter/10221/2 "2008-02-04T02:20:47Z")
Go back and make sure that when the air filter was changed that the intake hose wasn’t pulled loose/opened between the the filter housing and throttle body. Or that the Mass Airflow sensor was left unplugged or was damaged. This code indicates either there’s too much air entering the engine, or there’s a problem with the MAF sensor. Tester ---
**Author:** ![bwringer](https://avatars.discourse-cdn.com/v4/letter/b/e99b99/32.png) [@bwringer](https://community.cartalk.com/u/bwringer)\ **Post date:** [February 4, 2008, 4:35am UTC](https://community.cartalk.com/t/check-engine-after-new-air-filter/10221/3 "2008-02-04T04:35:20Z")
Seconded – it’s very easy to pull a vacuum line off or to disturb the intake hose while changing the air filter. If the intake hose was removed, it can be a little difficult to put back correctly. A few minutes with a flashlight should sort it out. ---
**Author:** ![glennallison](https://avatars.discourse-cdn.com/v4/letter/g/8797f3/32.png) [@glennallison](https://community.cartalk.com/u/glennallison)\ **Post date:** [February 5, 2008, 3:06am UTC](https://community.cartalk.com/t/check-engine-after-new-air-filter/10221/4 "2008-02-05T03:06:54Z")
Thanks both of you fellows…you are always there with good sound, common sense advice. Emmission guys went over it, but I think I will get in there and look for the loose connections, etc. that you suggested. If/when I get this resolved, I’ll post a note so every one can benefit. gla