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How To reset the 'engine light' after a repair has been made

Hi, can you tell me how to reset the ‘engine light’ after a repair has been made?

In most cars, you can disconnect the battery for 30 seconds and that will reset it. But that will also probably clear your radio channels. It may also reset your car’s computer which means it might idle a little differently until it goes thru its thing and acquires the needed setting.

A better way, and on many newer cars, the only way, is to use a scan tool to erase the trouble codes. Those auto parts stores which will read codes, can read and erase your codes.

The Auto Zones in my city refuse to erase codes,read only. Corporate policy stated.

Most codes will reset after a number of drive cycles.  A drive cycle includes starting and driving the car for a minimal distance and shutting it off. I believe some require a cool down between drives as well.  Normally a week of normal driving will re-set it IF there is no additional problem.

Who did the repair? You or a repair shop? If a repair shop did the repair they should have cleared the code and reset the light.

Wal-Mart is selling the Innova scanner for about $98. It comes with instructions. When you reset the code, all the indicator lights will be flashing.

If you have to get a smog check, you can leave the thing connected and drive it until the lights stop flashing. Drive cycle can be done in about 20 minutes, according to the manual that came with the thing. If smog check isn’t due for six months, you can disconnect the thing and the drive cycle will probably be completed by then.

People probably return the thing to Wal-mart because they think it is broken because of the flashing indicators.

Yup, I had this happen to me too. They used to erase codes, but they too quoted “corporate policy” in refusing to erase them this most recent time.

Supposedly people were coming by there on the way to get emissions tested with a lit CEL, having the Autozone people clear the codes, and then zipping to get the car passed thru emissions before it came back on. Great way to ruin it for everybody.

If you are preparing to get an IM test done you need to be aware that resetting the ECU will also clear the monitors and some of them at least will need to be set again before you can qualify for testing. If enough monitors are not set in the ECU the testing stops there. I think some testing stations require more monitors to be set than others, depending on what state you are in. Setting the moniors can take awhile and may require a number of driving cycles. There are procedures that can be followed to speed up the tests but the testing station or dealer service may be only places to have that info.

If you work on your own vehicles you should consider purchasing a good scanner so you can see if your repair work made a change or not. The scanner will show you if the error codes have changed. If the system is ok with the fix then it may require a few drive cycles before the CEL light turns off. The CEL light does not turn off instantly for some of the corrected error codes. A few driving cycles with no code errors may be required before the light turns off. The monitors will not be affected using that method. If you don’t have a IM test planned in the near future then resetting the ECU shouldn’t be problem.

Exactly right & I was curious about how many drive cycles it might take.

I loosened the gas cap on my wifes 02 Sonata & waited for the CEL to come on.

Tightend the cap & 3 days & 8 starts later the CEL went off.

So in the case of an 02 Sonata 8 drive cycles is apparently the magic number.