S2000 Under The Hood S2000 Technical and Mechanical discussions.

How To: Clear the ECU/CEL - Relearn ECU

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Old Dec 9, 2007 | 02:33 AM
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Default How To: Clear the ECU/CEL - Relearn ECU


(Not actual image)

To reset the CHECK ENGINE LIGHT (CEL) OR ECU Clear/ECU Reset (after a "Map Whack") -> Both the Same Procedure.


First red circle, you can see a picture of an engine with "CHEC" inside.



Before you reset the light, Pull the code - either yourself with a scan tool, Autozone/Advanced/etc, or your local Stealership.

Let's get started: On the left side footwell kickpanel you will notice this.



- Right Column - Third One down Labeled "BACK UP"(7.5amp)

- Now up and under the dash, is the fuse block itself. Here are two pics but there is only 1 Fuse, its just different angles - both circled in Red. Ignore the yellow arrow....or you can use it as reference and the Back Up fuse is below the 15amp it's pointing at.




- Make certain the key is in the OFF position and then pull the Back Up fuse for a couple minutes (just to be safe) then press it back in place.



(for those who have never replaced a fuse....here is a pic provided by CKit, showing the location of the handy little guy.)

You have now cleared the ECU, the CEL should now be off, if it does come back on you probably have something a little more serious, then say a loose gas cap. But you should know the problem because you had the code read first, right?

**If you are Clearing the ECU d/t rough idle or other than getting rid of that pesky CEL, you'll want to keep reading.

So, you have the Back Up Fuse pulled out for a few minutes, following the exact process above.....and pressed it back in.

Start the car - BUT keep everything OFF, radio - headlights - nothing plugged in the Accessory Outlet, etc. Let the car idle for 5-6 mins (to be safe.) This allows the ECU to LEARN and adjust to the new settings or whatever you have modded, changed, or Whacked.

[QUOTE=pemex70]
Old Dec 9, 2007 | 02:56 AM
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When I read the title I thought, "He's a moderator... shouldn't he know how to reset the CEL... and that it's not the same thing as the Maint light?"

Old Dec 9, 2007 | 02:59 AM
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Here's a pic I made for dyhppy a while back. Feel free to use it.

Old Dec 9, 2007 | 03:31 AM
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What's wrong with discontecting the battery and pressing on the gas like other cars?
Old Dec 9, 2007 | 06:55 AM
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Pulling the fuse requires no tools. The puller is already in the fuse box.

Pressing the gas in completely unnecessary.
Old Dec 9, 2007 | 10:41 AM
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Thanks CKit. I never knew that much detail would be required



Originally Posted by LittleBluePill
What's wrong with discontecting the battery and pressing on the gas like other cars?
Because it's wrong, and a pain in the ass.
Old Dec 9, 2007 | 12:20 PM
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Originally Posted by NVMY4N,Dec 9 2007, 11:41 AM
Thanks CKit. I never knew that much detail would be required
Well, it was for dyhppy....

And disconnecting the battery resets a whole bunch of other things like the radio (needing code), etc. PITA. Fuse is easier. Actually OBD-II scanner is even easier than that....
Old Dec 9, 2007 | 12:26 PM
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Honda Shop Manual recommends after start up to rev the motor to 3K and hold it until the fan kicks in and then let it idle for 5min. without counting the time the fans kick back on during those 5 minutes.
Old Dec 9, 2007 | 01:49 PM
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Originally Posted by pemex70,Dec 9 2007, 04:26 PM
Honda Shop Manual recommends after start up to rev the motor to 3K and hold it until the fan kicks in and then let it idle for 5min. without counting the time the fans kick back on during those 5 minutes.
All this really does is to Warm the engine quicker.....to get the Cooling Fans to cycle.
Old Dec 9, 2007 | 04:38 PM
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Originally Posted by NVMY4N,Dec 9 2007, 02:49 PM
All this really does is to Warm the engine quicker.....to get the Cooling Fans to cycle.
Yes, the Honda Tech said running the motor at 3K will let the ECM learn the mods to set the timing n a/f ratio at a 'safe' level.

I ran it once with a header, test pipe, and single exhaust and it popped and was raspy between shifts and after doing this it did settle down a bit and didnt pop between shifts.
Maybe Im skeptical cause I usually dont believe everything Tech's say.

Just like the rest of the info here, take my advice with a grain of salt.



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