# EVAP fault code. How many starts to self-clear? **URL:** \ **Category:** Factual Questions\ **Created:** [May 11, 2017, 5:00pm UTC](https://boards.straightdope.com/t/evap-fault-code-how-many-starts-to-self-clear/786370 "2017-05-11T17:00:46Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [May 11, 2017, 5:00pm UTC](https://boards.straightdope.com/t/evap-fault-code-how-many-starts-to-self-clear/786370/1 "2017-05-11T17:00:46Z")
Wife’s car just threw a code today for an evap emissions system leak. Fuel cap seemed tight, but I snugged it up again anyway. It’s been maybe ten years since I dealt with this on a previous car, but ISTR this code will clear on its own after X key starts. Anyone know the value of X? Or am I remembering wrong, and it’s X key starts with a persistent problem before the MIL comes on (and I’ll have to borrow a reader to reset it)? ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [May 11, 2017, 5:07pm UTC](https://boards.straightdope.com/t/evap-fault-code-how-many-starts-to-self-clear/786370/2 "2017-05-11T17:07:42Z")
I’ve heard it’s three key starts with some kind of genuine mileage on each. Big help, I know! ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [May 11, 2017, 5:09pm UTC](https://boards.straightdope.com/t/evap-fault-code-how-many-starts-to-self-clear/786370/3 "2017-05-11T17:09:31Z")
> [@Leaffan](#): > > I’ve heard it’s three key starts with some kind of genuine mileage on each. Three starts to trigger the MIL, or three starts to clear it (or both)? ---
**Author:** ![Dallas\_Jones](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dallas_jones/32/3277_2.png) [@Dallas\_Jones](https://boards.straightdope.com/u/Dallas_Jones)\ **Post date:** [May 11, 2017, 5:22pm UTC](https://boards.straightdope.com/t/evap-fault-code-how-many-starts-to-self-clear/786370/4 "2017-05-11T17:22:37Z")
As usual for car questions you should tell us what year, make, model, engine. The EVAP code should clear in 3 driving cycles on most cars. A driving cycle is NOT 3 key starts. A driving cycle allows time for the computer to read the input from the sensors and run a diagnostic again. Here is an example of the drive cycle on a GM car. Just drive it like you normally do and it should allow time for the PCM to run a new test and reset the light. [http://obdii.com/drivecycle.html](http://obdii.com/drivecycle.html) ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [May 11, 2017, 5:26pm UTC](https://boards.straightdope.com/t/evap-fault-code-how-many-starts-to-self-clear/786370/5 "2017-05-11T17:26:18Z")
> [@Machine\_Elf](#): > > Three starts to trigger the MIL, or three starts to clear it (or both)? What **Dallas** said. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [May 11, 2017, 5:30pm UTC](https://boards.straightdope.com/t/evap-fault-code-how-many-starts-to-self-clear/786370/6 "2017-05-11T17:30:26Z")
> [@Dallas\_Jones](#): > > As usual for car questions you should tell us what year, make, model, engine. Sorry, you’re right. 2011 Honda CR-V, only 30,000 miles. I know OBD2 is mandatory for any car sold in the last couple of decades, so I figured the behavior (i.e. the # of [del]keystarts[/del] driving cycles required to set/clear an evap system fault) would be the same across all models. Is that not the case? ---
**Author:** ![Dallas\_Jones](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dallas_jones/32/3277_2.png) [@Dallas\_Jones](https://boards.straightdope.com/u/Dallas_Jones)\ **Post date:** [May 11, 2017, 5:47pm UTC](https://boards.straightdope.com/t/evap-fault-code-how-many-starts-to-self-clear/786370/7 "2017-05-11T17:47:22Z")
> [@Machine\_Elf](#): > > Sorry, you’re right. 2011 Honda CR-V, only 30,000 miles. I know OBD2 is mandatory for any car sold in the last couple of decades, so I figured the behavior (i.e. the # of [del]keystarts[/del] driving cycles required to set/clear an evap system fault) would be the same across all models. Is that not the case? Probably, I don’t know, I only know GM. Because an EVAP code is usually triggered by an air leak, like a loose gas cap, what your computer is looking for is I believe in step 4 of my GM example, air intrusive. Unless you are making real short trips your day-to-day driving should cover these drive cycles in a day or so. I wouldn’t worry about it unless it doesn’t go out after a week. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [May 12, 2017, 2:24am UTC](https://boards.straightdope.com/t/evap-fault-code-how-many-starts-to-self-clear/786370/8 "2017-05-12T02:24:27Z")
Note that with an OBD-to-Bluetooth device (~ $15) and the Torque smartphone app ( ~ $5) you can read & clear trouble codes at will. (That’s a very small part of what you can do, but definitely useful.)