nickjays

Greetings Community,

I was recently driving home late in the night when my A4 started running on three cylinders due to one of the coils expiring and the "Check Engine" light came on. It was rough getting home, since my car had no power to go up the one large hill on my way home. I drove a maximum of 30km/h, 10km/h uphill at about 1000RPM because minimal RPMs didn't cause the Audi to shake wildly.

The next day I installed the 50 dollar part and everything is working correctly but the "Check Engine" light is still on. I'm wondering if there is anyway to reset it without using a VAG-COM or similar Diagnostic tool to reset it.

I was also told that it's possible to disconnect either the positive or negative cable from the battery for 40-60 seconds to reset the computer, the only negative outcome of this mode of resetting it is one has to reprogram the stereo.



Thank you in advance,
Nick

kf3506

I've had check engine light (cel) came on twice due to rough start.
Did some research on other forum and found that some emission cel resets itself after a long drive.
I got rid of mine twice after a half hour drive.

nickjays

Thanks KF, I'll be sure to drive it around a bit this weekend, to see what happens.

I'll let you know if such is the case for my Audi as well.


-Nick

GPAUL

Did the CEL light reset? I've had mine come on from a rough start in the morning this week. It reset itself after I drove on the 401.

mikeh

There is a way to re-boot the computer by disconnecting both pos and neg battery leads, toughing them together (disipates stored energy in capacitors) for 30 seconds and then connecting them back up.

The hitch here is you should have your stereo code ready.

cheeba

You should do an oil change immediately, as there could be fuel in the oil now. I can't say that I recommend continuing to run your car when you know it's misfiring . . .

nickjays

Solved this problem by disconnecting the battery for a few minutes a long time ago which reset my computer.

I don't see why I would need to do an oil change... Don't the sensor recognize that a cylinder wasn't working so they "shut it off". I assume this because there was no fuel on the tip of the spark plug. A misfire wouldn't cause a mixture with fuel and oil since they are separated by the piston.

Correct me if I'm wrong,
Nick

cheeba

What sensor? I don't know of anything that shuts the fuel delivery to an individual cylinder off. That's not to say it doesn't exist, but I don't know of a system that does this. Un-combusted fuel will wash the cylinder walls, and can destroy rings and cylinder walls pretty quickly. It's your car, though - drive it while misfiring, and don't change a few dollars worth of oil, all you want...