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What are the goods and bads of resetting your cars ECU, what to do after reset?

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[OP]
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Dec 20, 2005
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What are the goods and bads of resetting your cars ECU, what to do after reset?

What are the good and bad sides of resetting your cars ecu? How long after the reset will the car re-learn again? Is there any symptoms that follow after resetting ECU? Any damages from it?
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Jan 14, 2009
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001Stunna wrote: What are the good and bad sides of resetting your cars ecu? How long after the reset will the car re-learn again? Is there any symptoms that follow after resetting ECU? Any damages from it?
i reset mine all the time. not sure why i do it. i mean, they should be constantly re-learning without being reset. the damage would be something stupid like you not tightening battery bolt or touching the positive to negative or something.
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Dec 12, 2006
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I've done mine once to reset the CEL as I didn't have an OBD2 reader handy. The CEL went away and never came back, nothing else happened.
Newbie
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Feb 23, 2005
74 posts
Markham
Some reported their cars drove smoother after a reset and some claimed an increase in fuel economy. Personally, I didn't feel anything different after I reset mine.

Depending on what vehicle you have, you might have to enter a radio code to unlock it after resetting the ECU, so make sure you have it handy.
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May 10, 2005
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Resetting the ECU is not something you should do as a mater of routine maintenance. You should do it to reset any error codes you may have, just to ensure they were not spurious errors. Also, a reset is recommended when you do any modifications to the car that will be "felt" by the ECU (injectors, catbacks, CAI, even just a drop in high flow air filter, etc)
You will need to drive the car 'gently" after a reset to enable the ECU to relearn the systems now.
The other thing, if you disconnect the battery for the reset, you need to configure all your radio presets and any others in the car. If you do disconnect the battery, the longer the better but at least an hour.
[OP]
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Well the reason why i asked was because i did the reset on my 99 accord lx after having a little issue with it. The only thing is after the reset now it feels like the car has a hard time accelerating and i really need to push the gas pedal to get it to go, it also feels like the car drives quite heavy. Im thinking maybe its just the gas and itll change once i refill but was wondering if anything couldve gone wrong due to resetting the ECU
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Deal Expert
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May 10, 2005
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001Stunna wrote: Well the reason why i asked was because i did the reset on my 99 accord lx after having a little issue with it. The only thing is after the reset now it feels like the car has a hard time accelerating and i really need to push the gas pedal to get it to go, it also feels like the car drives quite heavy. Im thinking maybe its just the gas and itll change once i refill but was wondering if anything couldve gone wrong due to resetting the ECU
I am thinking that you may have done something to make the ECU learn something you don't want. There is a process once you have disconnected the ECU. I am not sure on your model but, in general, some of the things is to start the car without touching the gas, let it idle for 5 minutes then shut it off. Restart the car, without stepping on the gas and then driving away without hammering down on the gas. Then just drive normal. It takes a while for the ECU to learn all the nuances all over again. Don't expect it to react the way it did before reset. It took a long time to get there.
Ask a shop or the dealer for the proper procedure for your specific car and engine.
[OP]
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Pete_Coach wrote: I am thinking that you may have done something to make the ECU learn something you don't want. There is a process once you have disconnected the ECU. I am not sure on your model but, in general, some of the things is to start the car without touching the gas, let it idle for 5 minutes then shut it off. Restart the car, without stepping on the gas and then driving away without hammering down on the gas. Then just drive normal. It takes a while for the ECU to learn all the nuances all over again. Don't expect it to react the way it did before reset. It took a long time to get there.
Ask a shop or the dealer for the proper procedure for your specific car and engine.
Well i asked around and did the following...
-Came back from a 30-40 min drive.
-Parked the car and disconnected the battery(wheels straight, windows rolled up, doors unlocked, all accessories turned off)
-Stepped on the brakes for 20-25 seconds
-Waited 15 minutes
-Re-connected the battery
-Turned the car on without pressing anything and let it run for 20-25 minutes.
-Turned the car off...waited 10-15 seconds
-Turned the car back on, moved the steering wheel fully to left, then fully to right then back to center. Rolled down windows fully. Rolled up windows fully. Doors Lock/Unlock.
-Let it run for 3-4 minutes and turned it off.
-Turned it back on and went for a 30-35 minute drive (no jackrabbit starts, normal driving behavior)
-Came home parked it and left it.

I think i'll give it another try again though maybe when its not -25C outside lol and see if maybe things go better
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Jan 14, 2009
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001Stunna wrote: Well i asked around and did the following...
-Came back from a 30-40 min drive.
-Parked the car and disconnected the battery(wheels straight, windows rolled up, doors unlocked, all accessories turned off)
-Stepped on the brakes for 20-25 seconds
-Waited 15 minutes
-Re-connected the battery
-Turned the car on without pressing anything and let it run for 20-25 minutes.
-Turned the car off...waited 10-15 seconds
-Turned the car back on, moved the steering wheel fully to left, then fully to right then back to center. Rolled down windows fully. Rolled up windows fully. Doors Lock/Unlock.
-Let it run for 3-4 minutes and turned it off.
-Turned it back on and went for a 30-35 minute drive (no jackrabbit starts, normal driving behavior)
-Came home parked it and left it.

I think i'll give it another try again though maybe when its not -25C outside lol and see if maybe things go better
i dont think it is good to let your car sit and run for a long time.
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May 10, 2005
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freeonboard wrote: i dont think it is good to let your car sit and run for a long time.
In fact, to reset the ECU, you do need to let the car run at idle for at least 10 minutes. The engine needs to warm up, the idle needs to stabilize and the ECU itself has to collect all new data from all the sensors over a period of time to begin functioning again.
The engine response will feel differently and maybe substantially in the beginning. That is because the ECU never stops learning and is constantly adjusting as you drive. Your ECU (before reset) has had what, 100,000 kms to learn your habits? Give it some time to adjust for all the driving habits you have. It may take a hundred kms.
The steering and windows and locks are a bit of a stretch for the engine control module and don't do it. You are just loading the engine during an engine idle data collection period. :)
Newbie
Feb 2, 2009
32 posts
I reset my ecu seasonally. late spring and winter. I may be a bit cookoo here, but I find the car running smoother after that. find the fuses that need to be pulled out instead of disconnecting the battery. that way you still keep all your radio presets.

the procedure for my beater is this. disconnect the battery (or pull out the fuses) for at least 5 min. do it for 10. hook it back up. idle for 10 minutes without any load!!! no ac or power draw. I like to do this after the car cooled down a bit but not completely. the reason for it, especially in the spring time is that I'm trying to avoid having the radiator fans kick in.

Also for the first 10 k or so my call will stall. then it'll learn to recover from sharp decels.

I'd do it again. run a cleaner, change the air filter, look at the plugs, reset it again.
Newbie
Aug 3, 2019
2 posts
001Stunna wrote: What are the good and bad sides of resetting your cars ecu? How long after the reset will the car re-learn again? Is there any symptoms that follow after resetting ECU? Any damages from it?
Usually I will pull the fuses then start it up put the vehicle in neutral let idle for 4 minutes go to low gear for 4 minutes let idle then drive the vehicle in drive over 30 MPH for atleast 20 min. Done

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