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Ask Peter Bagley Your Own Question
Peter Bagley
Peter Bagley, Toyota mastertech
Category: Subaru
Satisfied Customers: 188
Experience:  master tech at Toyota dealer
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I have a 2007 Outback. I disconnected the battery yesterday

Customer Question

I have a 2007 Outback. I disconnected the battery yesterday to change the bulb in the driver side headlight. Today, my wife is reporting that the car runs very poorly (misfire, cannot start from iddle,...). Any clue?
JA: Have you changed a battery before?
Customer: Yes it was done a couple of years ago.
JA: Are you fixing your Outback yourself? What have you tried so far?
Customer: Nothing it is my wife's car and I did not check it since yesterday
JA: Anything else you want the mechanic to know before I connect you?
Customer: not really
Submitted: 4 days ago.
Category: Subaru
Expert:  Peter Bagley replied 4 days ago.

Hello and welcome to just answer and allowing me to assist you.I may need to ask questions to get a better picture to help.When you replace or disconnect a battery the ECU goes through a time of relearning all the inputs and driving habits to control the engine managements. Also in some cases if it does not correct itself the throttle body builds up deposits that need to be cleaned .This can be done using a proper throttle body cleaner sprayed into the opening using a tooth brush cleaning it while holding the throttle plate open.. use a light to see inside to make sure it's all clean.

Customer: replied 4 days ago.
Should we continue to drive until it relearns itself?
Expert:  Peter Bagley replied 4 days ago.

If that is the issue after driving a coupls times it should, but like I said if it don't then next step is to clean the throttle body as in the video I sent, varnish restricts the plate from returning to original position and the ECU does not recognize this.