How can I clear the ECU without a dealership?

You can clear error codes and warning lights with most OBDII readers. I recently bought a nice one for about $100 or $150. Here is the one I have, although I think I found it on ebay for a bit less:

http://www.amazon.com/gp/product/B0007VXZ7W/002-3100977-4679245?redirect=true

Ray

 

Disconnect the battery.

 

I have the same reader and it is excellent. A must have for an F-car owner. You can read your own codes. Once you know the code you can make an informed decision about clearing it. Get one at your local Pep Boys about $150.

 

"Listen to me now and believe me later!"
Unplug it and see. Leave it unplugged for a few minutes just in case.

 

Disconnecting the battery will not clear error codes recorded on OBD II systems, the error codes are stored in the ECU until such time as they are cleared and power to the ECU has nothing to do with how and where they are stored. On earlier OBD I systems you could sometime clear the indicator light for the error but the ECU will continue to store the info for reading later. The method of clearing the ECU by disconnecting the battery and holding the leads together is an urban myth, todays ECU's are much more advanced than that.

 

On what car?
Works fine for me in my fleet of test vehicles and they're all OBD II. I'm dubious Ferrari is overachieving on their OBD implementation. That's why code 1000 (OBD readiness not complete) exists is to keep drivers from disconnecting their battery just before going for an emissions test. Otherwise it would be easy to beat many codes in states where they plug into your OBDII to get your annual certification.

 

I spent the better part of a year working with a very well known chip tuner on programming for MINI's. We were a new company at that time and were lucky enough to have a Mustang Dyno and OBDII readers in house for our testing and development, as well as the support and help of two local dealers. The only thing that we were able to clear with a battery disconnect was the learned adaptation values for the learned patterns of the driver. Other than fuel trim and timing, all of the values and faults were stored to be recalled later. Even though the fault light could be turned off it had little to do with the stored fault code being deleted from the ECU itself. I am in no way claiming to be an ECU expert and all of the systems that I have dealt with were much more complex than my ability to fully understand them, and that is why we worked with the best people we could on these things. These are just my experiences here and not the law of the land. The better ECU readers allow you to look much deeper into the memory then the less costly ones, and this is where much of the learning is at.




Thanks

 

Hard memory for error codes is no longer required. It has been that way since at least 99. We first became aware of it with the 360's when it was found quite by accident that error memory was erased with battery shutoff. The 360 was built with a brand new version motronic. The 550 at the time was still using an old version so they still had a hard memory. Any car still using a system more than 7 years old may still have a hard error memory but it is no longer a federal requirement.



360 turning off the battery will erase error memory.

550 it will not.

 

Reread #11

 

Your first post is confusing. Were you getting a check engine light due to a cat overheat signal?
If it is just a slow down light, that is different than a check engine light triggered buy the Motronic.
A slow down light has only one control and that is the cat temp ECU. That requires no reset. If it is on all the time a component needs replacement, but there is more than one component. Some diagnosis is required to determine which one. If it is on sometimes, it needs to be diagnosed for a cause.


Oddly enough sometimes when a red light is on it really means something is wrong. An airline pilot once told me if an instrument indicates a failure it is almost certainly an instrument failure but only a stupid, soon to be dead pilot does not believe his instruments. Not calling anyone stupid but more information is needed. Just throwing parts at a car to fix it gets expensive.

 

Perhaps you asked the wrong question initially? I thought the issue was how to clear a check engine light? Easy answer, given several times. Purchase/borrow an OBD II reader.

I gather based on the above that the question you meant to ask was "How do I clear a check engine light using only what I currently own in my toolbox/garage/workshed?" Ah! Now I get it. You're looking for the time-honored "lazy and cheap" solution. A true American Gearhead, my hats off to you.

Simple. 1) drill small hole in your gauge cluster. Might want to use some tape to keep the plastic from splintering. 2) Take an ice pick, carefully push this through the hole to the check engine light. 3) Lobotomize the check engine light. Be sure to twist the ice-pick vigorously, as you're goal here is to destroy the actual bulb element while doing as minimal damage to the rest of your cluster as possible. Done properly, the check engine light will now be extinguished.

See, we F-chat guys can be super-helpful! You just have to ask the right, specific question.