# Open Loop/Closed Loop Question **URL:** \ **Category:** Power/Fuel\ **Created:** [December 19, 2020, 11:51pm UTC](https://community.cartalk.com/t/open-loop-closed-loop-question/173451 "2020-12-19T23:51:08Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![ArgosNoble](https://avatars.discourse-cdn.com/v4/letter/a/a88e57/32.png) [@ArgosNoble](https://community.cartalk.com/u/ArgosNoble)\ **Post date:** [December 19, 2020, 11:51pm UTC](https://community.cartalk.com/t/open-loop-closed-loop-question/173451/1 "2020-12-19T23:51:08Z")
Hi all!! Just curious. Do cars switch to Open Loop when in Park/Neutral? ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [December 20, 2020, 12:16am UTC](https://community.cartalk.com/t/open-loop-closed-loop-question/173451/2 "2020-12-20T00:16:19Z")
No, they switch into closed loop when the car warms up enough to switch. Doesn’t matter what gear its in. I believe that some go open loop at full throttle but I think that info is only for older ecu controlled cars. ---
**Author:** ![ArgosNoble](https://avatars.discourse-cdn.com/v4/letter/a/a88e57/32.png) [@ArgosNoble](https://community.cartalk.com/u/ArgosNoble)\ **Post date:** [December 20, 2020, 1:15am UTC](https://community.cartalk.com/t/open-loop-closed-loop-question/173451/3 "2020-12-20T01:15:56Z")
@Mustangman Thank you!! ---
**Author:** ![ArgosNoble](https://avatars.discourse-cdn.com/v4/letter/a/a88e57/32.png) [@ArgosNoble](https://community.cartalk.com/u/ArgosNoble)\ **Post date:** [December 28, 2020, 5:44pm UTC](https://community.cartalk.com/t/open-loop-closed-loop-question/173451/4 "2020-12-28T17:44:10Z")
How long should it take for a car to switch to closed loop on a cold start?? ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [December 28, 2020, 7:16pm UTC](https://community.cartalk.com/t/open-loop-closed-loop-question/173451/5 "2020-12-28T19:16:46Z")
> [@ArgosNoble](#): > > How long should it take for a car to switch to closed loop on a cold start?? Late model cars with heated oxygen sensors, no more than a minute or two. My 2017 Hyundai Tucson takes about 45 seconds. Earlier models, like the 1988 Accord I used to have, can take several minutes, depending on whether they are driven promptly or left to idle. ---
**Author:** ![ArgosNoble](https://avatars.discourse-cdn.com/v4/letter/a/a88e57/32.png) [@ArgosNoble](https://community.cartalk.com/u/ArgosNoble)\ **Post date:** [December 28, 2020, 7:29pm UTC](https://community.cartalk.com/t/open-loop-closed-loop-question/173451/6 "2020-12-28T19:29:01Z")
@circuitsmith How long would you guess it should take for a 2011 Toyota Camry LE 4 Cylinder? ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [December 28, 2020, 10:19pm UTC](https://community.cartalk.com/t/open-loop-closed-loop-question/173451/7 "2020-12-28T22:19:04Z")
No more than a minute or two. ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [December 28, 2020, 11:53pm UTC](https://community.cartalk.com/t/open-loop-closed-loop-question/173451/8 "2020-12-28T23:53:13Z")
Maybe 2 minutes if it is a cold day… The faster it gets to open loop, the better the fuel economy and the lower emissions the car produces… ---
**Author:** ![JoeMario](https://avatars.discourse-cdn.com/v4/letter/j/3bc359/32.png) [@JoeMario](https://community.cartalk.com/u/JoeMario)\ **Post date:** [December 29, 2020, 12:39am UTC](https://community.cartalk.com/t/open-loop-closed-loop-question/173451/9 "2020-12-29T00:39:27Z")
After an engine is started, there is an EPA-specified upper limit on the time to transition from open to closed loop. I recall it’s specified in a way allow for differences in engines. I don’t remember if operating conditions were part of that spec. [Updated to switch the open and closed terms. I accidentally wrote them in backwards] ---
**Author:** ![ArgosNoble](https://avatars.discourse-cdn.com/v4/letter/a/a88e57/32.png) [@ArgosNoble](https://community.cartalk.com/u/ArgosNoble)\ **Post date:** [December 29, 2020, 3:03pm UTC](https://community.cartalk.com/t/open-loop-closed-loop-question/173451/10 "2020-12-29T15:03:08Z")
@circuitsmith Can a faulty O2 Sensor work fine when immediately switching to closed loop but then start to malfunction and send incorrect data when the car reaches operating temperature? ---
**Author:** ![Mustangman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mustangman/32/44130_2.png) [@Mustangman](https://community.cartalk.com/u/Mustangman)\ **Post date:** [December 29, 2020, 3:48pm UTC](https://community.cartalk.com/t/open-loop-closed-loop-question/173451/11 "2020-12-29T15:48:37Z")
O2 sensors don’t work when cold so they aren’t used for open loop control. That is the definition of “open loop.” The loop is closed when a down-stream sensor provides accurate information that allows the controls to adjust. The open loop control uses a look-up table capable of running the engine without the O2 sensor. ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [December 29, 2020, 7:53pm UTC](https://community.cartalk.com/t/open-loop-closed-loop-question/173451/12 "2020-12-29T19:53:52Z")
@ArgosNoble maybe you should cut to the chase and describe the problem you’re having. Give us make, model, year, mileage, symptoms, trouble codes, scanner readings, etc.