Hi:

Recently I went away for a week, left my 1997 Subaru @ the airport. When I can back....battery dead. So after a jump and a few days of trying to recharge the battery I went and got a new one.

Haven't driven the car much for a month or so, then I had to get my Dept of Motor Vechicles smog test.

It failed and the testor told me that everything checks out except the onboard computer is not reporting any codes.

He said I should drive the car for a hundred miles or so and retest.

I understand that replacing the battery would reset the computer.......is there anything I should do to get it active again? Is there was a procedure for doing this? ...........before I go on a wasted drive?

Thks.

 

Just drive around for a tank...should be fine after that.

I did read that stuff doesn't get stored till after 100 miles...but might as well waste a full tank so you don't have to pay for a smog recheck 3 times...

fibuz

 

Yeah, replacing the battery (or, more accurately, removing the batter connection for long enough for the ECU to lose power), causes the ECU to reset.

When it resets, everything is put into a 'non-ready' mode. The car needs to be driven for some length of time (usually one tank) before the ECU goes back into 'ready' mode. They do this to prevent people from just clearing their ECU and smogging it before another CEL pops up. There is really no way around it other then to drive it.

 

what your computer is not reporting are monitors. There are several. Some are monitored continuously and some are sampled under certain conditions or by drive cylcle, or by trips.

I could almost guarantee that your O2 sensor, O2 heat monitor, and Egr monitor have not run since your battery died. When your battery died.... your computer "forgot" that these systems were working correctly.

Drive it... they'll record themselves.

 

Hey Thanks for the replies guys.
I really appreciate it. It never occured to me, especially since after replacing the battery I have hardly driven it een though it's been over a month.
My Kid went to college and since it became his car I guess I don't want to drive it,
makes me think of him when I'm trying to let go.

I'll do a drive and repost after a tank.

Thks again

 

Hey guys,

Thanks for cluing me in. I drove the car as recomended ....about 190 miles
various conditions and went back again for the smog.

It passed and I'm glad thats over.

Thanks again for your help.

 

Glad to hear it.