Check Engine Light

I need some information about the CEL. I have been told there are soft codes and there are hard codes. Soft codes have only occurred once and no longer exist. I've been told it takes 40 cycles of starting your car to erase a soft code. Or, you could take the negative battery terminal loose for 15 minutes to make the light go out. A hard code is when a malfunction occurs and is ongoing. It can be erased, too, but will come back on. Does anyone know for sure about these things? My Haynes manual says you should not erase codes this way on 1.9 engines. I wonder why not? Many times it is specified to take the negative terminal loose before doing various things to the car. What's the difference?

I need some information about the CEL. I have been told there are soft codes and there are hard codes. Soft codes have only occurred once and no longer exist. I've been told it takes 40 cycles of starting your car to erase a soft code. Or, you could take the negative battery terminal loose for 15 minutes to make the light go out. A hard code is when a malfunction occurs and is ongoing. It can be erased, too, but will come back on. Does anyone know for sure about these things? My Haynes manual says you should not erase codes this way on 1.9 engines. I wonder why not? Many times it is specified to take the negative terminal loose before doing various things to the car. What's the difference?

Dave.
The soft codes are the ones that havent triggered the check engine light. They are accesable when you use the code reader. The hard codes are ones that have triggered the light. In my experience if the problem is corrected the light will usually reset itself in about 3 days or so. Those numbers of 40 cycles seem high. I have had my 96 since it was new and only had 2 codes show. One for the egr valve flow, another for the vent for the fuel.
Ralph

That answers my question. Thanks for the reply. Dave

Dave..not 100% sure about 97's(obd11) BUT! this is for obd 1's.
When the cel comes on.Period.Even for a split second.Yes..you may miss it.IF it goes out..THIS is a soft code.A code stored in the computer.These codes will get automatically erased..after SO many start-ups..can't remember off the top of my head..PROVIDING that the code has not come up again.These codes are stored can be retreived/erased..without fixing anything.And you are back to normal..till the cel comes on again..yes you may miss it and it may again find it's way back into the memory.

MANY! a consumer has been BADLLY!! burned by dishonest garages during emmissions testing!..The garage will "just sort of happen"..to GO LOOKING..and see a soft code in the computer with no cel.They then tell the customer that there is an emmission related code in the computer and the car cannot pass emmissions with a cel on and it MUST have come on for it to trigger a code.When they print this out tough for the average person to argue.

When the cel comes on and stays on this is a hard code.Almost always with a hard code..ya gotta fix it ONCE you get a cel.

There are specific soft and hard codes.Can't remember off the top of my head for that either.Some codes..the more serious ones.The cel comes on stays on.Ya gotta fix the problem.IF you simply erase the code..that is ok..AND YES! people do that and then say when they sell the car that it won't start/out of gas/dead battery etc., ETC.,..."OH NO..NEVER any CEL"..Problem is..soon as you expose the computer to that fault again...on comes the light.NOW who can really say when the problem occurred?

Soft codes can come and go..BIG PROBLEM with these little gremlins..is IF you leave it..cel coming on..off..erasing.. making mistakes when you read the codes..the computer and sometimes other sensors will start trying to compensate..or failing too..HEHEHAHA..this can leave you so many stinkin' codes that it is next to impossible to record them all..SOoo..you just erase them..ANd a bunch come back QUICK AGAIN!..

I have a cel that comes on and off..certain driving can trigger or erase it.ROFL..LMAO..I have left this for a long time..amd not retreived the codes or fixed anything..I am PRETTY sure what I will find when I check..