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A lot of new cars have throttle bodies (air control butterfly valves) that are opened and closed by a small electric motor instead of a cable connected to the foot pedal like older cars. After a battery goes dead, this motor needs to "find" where it is so it can be adjusted by the engine's computer. My 2005 Subaru just had this problem... and after some searching on the internet I found the solution. Many other manufactuer's cars have this same problem.

After changing the battery, turn the ignition switch on for 10 seconds berfore turning over the engine. This gives the electrical motor time to go to home position. After 10 seconds start the engine, let the engine idle with NO LOAD (AC, lights etc.) for 10 minutes so the computer can adjust the engine settings to optimum position.

This solved my problem on my Subaru for $0 and I am so glad a Subaru technician took the time to post the answer. Even if you have a new battery installed already, just disconnect the negative cable, wait 5 minutes and start over as I described above.

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โˆ™ 2014-05-15 02:04:55
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Q: What would cause the car to idle low after replacing the battery?
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