# Subaru won't start **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** legacy, subaru\ **Created:** [November 17, 2012, 6:01am UTC](https://community.cartalk.com/t/subaru-wont-start/75576 "2012-11-17T06:01:02Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![bloom2003](https://avatars.discourse-cdn.com/v4/letter/b/3be4f8/32.png) [@bloom2003](https://community.cartalk.com/u/bloom2003)\ **Post date:** [November 17, 2012, 6:01am UTC](https://community.cartalk.com/t/subaru-wont-start/75576/1 "2012-11-17T06:01:02Z")
In the couple of days since my last oil change, my 2003 Subaru Legacy (161K miles) won’t start after sitting for some time. It turns over and runs for literally one second, then dies. It is standard transmission. If I have it out of gear and apply gas, it will start and stay started, but if I take my foot off the gas, it stops. I don’t have to apply a lot of gas (not floor it). Once it is warmed up it runs fine. It seems to start fine if it sits a little while, but anything over an hour, and it doesn’t start. Any ideas? One place I read said it could be the security system, with my key needing to be re-programmed. Other possibilities seem all over the map. ---
**Author:** ![RemcoW](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/remcow/32/2471_2.png) [@RemcoW](https://community.cartalk.com/u/RemcoW)\ **Post date:** [November 17, 2012, 6:43am UTC](https://community.cartalk.com/t/subaru-wont-start/75576/2 "2012-11-17T06:43:32Z")
Could be a couple of things. One of the easier things to check is the Mass Air Flow sensor. You basically unplug it and then start it so see if wants to stay running. Do you know where it is located on your car? I can probably find a picture for you, if you don’t know. Edit: forgot to ask - is the check engine light on? ---
**Author:** ![RemcoW](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/remcow/32/2471_2.png) [@RemcoW](https://community.cartalk.com/u/RemcoW)\ **Post date:** [November 17, 2012, 6:48am UTC](https://community.cartalk.com/t/subaru-wont-start/75576/3 "2012-11-17T06:48:18Z")
Number 5 in the drawing. The check engine light may come on but that’s normal. Plugging it back in and leaving the battery disconnected for a while will reset it. ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [November 17, 2012, 7:08am UTC](https://community.cartalk.com/t/subaru-wont-start/75576/4 "2012-11-17T07:08:00Z")
My guess would be a vacuum leak or problem with the Idle Air Valve circuit. ---
**Author:** ![RemcoW](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/remcow/32/2471_2.png) [@RemcoW](https://community.cartalk.com/u/RemcoW)\ **Post date:** [November 17, 2012, 7:11am UTC](https://community.cartalk.com/t/subaru-wont-start/75576/5 "2012-11-17T07:11:40Z")
Could also be the temperature sensor. Edit: although, now that I think about it, a bad temperature sensor on a Subaru usually shows itself by starting and stalling. No amount of throttle will keep it running. Eventually it will start but that just means it gets into limp mode so it probably isn’t the temp sensor. ---
**Author:** ![bing](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bing/32/4619_2.png) [@bing](https://community.cartalk.com/u/bing)\ **Post date:** [November 17, 2012, 7:19am UTC](https://community.cartalk.com/t/subaru-wont-start/75576/6 "2012-11-17T07:19:58Z")
If you think about what inputs are used or not used during cold starting and then what inputs are used after closed loop or after warmed up, it’ll narrow it down. I’d be looking at the engine temp sensor too. ---
**Author:** ![Barkydog](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/barkydog/32/2470_2.png) [@Barkydog](https://community.cartalk.com/u/Barkydog)\ **Post date:** [November 17, 2012, 8:02am UTC](https://community.cartalk.com/t/subaru-wont-start/75576/7 "2012-11-17T08:02:50Z")
Try leaving the key in the on position 10 seconds before starting, If it works fine probably a new fuel pump. ---
**Author:** ![RichHill](https://avatars.discourse-cdn.com/v4/letter/r/6f9a4e/32.png) [@RichHill](https://community.cartalk.com/u/RichHill)\ **Post date:** [November 17, 2012, 12:51pm UTC](https://community.cartalk.com/t/subaru-wont-start/75576/8 "2012-11-17T12:51:29Z")
Read your owners manual about the alarm system. ---
**Author:** ![Cougar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cougar/32/21348_2.png) [@Cougar](https://community.cartalk.com/u/Cougar)\ **Post date:** [November 17, 2012, 1:35pm UTC](https://community.cartalk.com/t/subaru-wont-start/75576/9 "2012-11-17T13:35:02Z")
Try replacing the fuel filter if that hasn’t been done in a while. ---
**Author:** ![bloom2003](https://avatars.discourse-cdn.com/v4/letter/b/3be4f8/32.png) [@bloom2003](https://community.cartalk.com/u/bloom2003)\ **Post date:** [November 17, 2012, 6:06pm UTC](https://community.cartalk.com/t/subaru-wont-start/75576/10 "2012-11-17T18:06:38Z")
Thanks for all the ideas. I will try them today, and post what I find. The check engine light is not on. And I had thought this morning when I woke up that I should look at the manual about the security system! Silly me. Thanks again!