Replaced battery, Now Check Engine Light is On

Y

ykr1

New Member

Oct 21, 2003

18

0

1

Trenton, Nj

Nov 30, 2010

#1

• Nov 30, 2010

• #1

Hey Guys,

I recently replaced my battery on a 2005 GT. As soon as i did this i noticed that the car felt like it was driving a little weird and was idling at a lower RPM then normal. I just assumed that it was all in my head and didn't think anything of it. A few hours later... The check engine light came on. I think its pretty safe to assume that the check engine light has something to do with the battery swap. The car was running perfect prior to this. Any help you guys can give would be greatly appreciated! Thank you in advance.

PS- Its not my gas cap

 

N

nick08mustangGT

New Member

Nov 27, 2010

12

0

0

Dec 1, 2010

#2

• Dec 1, 2010

• #2

just wondering why did you change the battery...and it could be a bad battery, somtimes a store has batteries that have been sitting around for too weak for too long and they lost their juice, or you got a battery that is too weak for the car...did u check the volt rating?....and if u want ur check engine to go away just disconnect the battery for 30 sec then put it back on and the check engine light will turn off.

 

Y

ykr1

New Member

Oct 21, 2003

18

0

1

Trenton, Nj

Dec 1, 2010

#3

• Dec 1, 2010

• #3

Well My main concern is the low idle problem. Every once in a while it even stalls out when i stop. I really dont think its a bad battery but i guess i can swap it out. I will also try to disconnect the batter again.

 

streethorse

15 Year Member

Oct 8, 2005

1,042

6

58

Dallas Texas

Dec 1, 2010

#4

• Dec 1, 2010

• #4

Try the battery disconect, wait 5 minutes, step on the brake to discharge
all power, reconect, if the light is still on, get the code read at A-zone.free.

 

S

ski

Member

Dec 14, 2004

380

2

18

Dec 2, 2010

#5

• Dec 2, 2010

• #5

The ECU has to re-learn the idle strategy after the battery is disconnected. 20-50 miles of driving after the battery is reconnected usually gets the erratic idle back to normal. The CEL should also go out when that happens, or soon afterwards.
There's also a procedure in the battery maintenance section of the owner's manual that may expedite the ECU's re-learning process.

 

Y

ykr1

New Member

Oct 21, 2003

18

0

1

Trenton, Nj

Dec 3, 2010

#6

• Dec 3, 2010

• #6

Thank you Ski. I pulled the battery again to see if that would help. The check engine light is off now but the car is still idling low. I will give it a few more days and see if the computer re-learns, then report back. Appreciate the help from everyone, these boards are the best!

 

S

ski

Member

Dec 14, 2004

380

2

18

Dec 4, 2010

#7

• Dec 4, 2010

• #7

You're welcome. Keep us informed.

 

Y

ykr1

New Member

Oct 21, 2003

18

0

1

Trenton, Nj

Dec 14, 2010

#8

• Dec 14, 2010

• #8

Well, I have about 500 Miles of driving on the car since the pull. Still no check engine light but the car still seems to be idling low. When i come to a stop it wil dip below 500 and settle around 600 RPM. Any other suggestions? Do you think i have to adjust the Throttle Position Sensor?

 

S

ski

Member

Dec 14, 2004

380

2

18

Dec 15, 2010

#9

• Dec 15, 2010

• #9

The throttle body may need cleaning. Auto parts stores sell sprays designed specifically for this purpose. Also clean the MAF sensor.

 

M

mjtroll

New Member

Apr 13, 2018

2

0

1

chicago

Apr 13, 2018

#10

• Apr 13, 2018

• #10

I have 2005 mustang gt and just had passenger air bag replaced which required battery disconnect..the engine light came out within a few days and the scan said I believe P506 which indicated idle was running under spec (which it was).. my mechanic suggested that the throttle body be cleaned which it was and then after it was first thought the throttle body needed to be replaced (several hundred dollar repair) the light went off and so far so good