# Check Engine Light on 02 Forester w/ 90,000 **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** forester, engines, subaru, lights\ **Created:** [April 26, 2011, 4:25pm UTC](https://community.cartalk.com/t/check-engine-light-on-02-forester-w-90-000/64094 "2011-04-26T16:25:12Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Wayniac](https://avatars.discourse-cdn.com/v4/letter/w/90ced4/32.png) [@Wayniac](https://community.cartalk.com/u/Wayniac)\ **Post date:** [April 26, 2011, 4:25pm UTC](https://community.cartalk.com/t/check-engine-light-on-02-forester-w-90-000/64094/1 "2011-04-26T16:25:12Z")
Engine light came on two weeks ago. Had the code read at Advance Auto Parts. Code = P0420. The only performance issue was that it stalled when I started it the other day for the first time since I bought it last fall. Are there any other clues to tell what it could mean (catalytic converter vs. 02 sensor vs. anything else)? Is it really worth trying some kind of catalytic converter cleaner product? ---
**Author:** ![common-sense-answer](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/common-sense-answer/32/716_2.png) [@common-sense-answer](https://community.cartalk.com/u/common-sense-answer)\ **Post date:** [April 26, 2011, 5:38pm UTC](https://community.cartalk.com/t/check-engine-light-on-02-forester-w-90-000/64094/2 "2011-04-26T17:38:49Z")
Link To Code Help: > **[P0420 Catalyst System Efficiency Below Threshold](https://www.obd-codes.com/p0420)** > > How to diagnose, repair, and info on symptoms and causes of a P0420 engine code which means the catalytic converter is no longer performing at a normal level. Home page link - PO420 is a Top Ten requested DTC: > **[OBD-Codes.com the leading OBD-II trouble code resource site](https://www.obd-codes.com/)** > > We help you diagnose vehicle repair issues by providing detailed OBD-II trouble code articles and a free discussion forum to ask questions. CSA