disconnecting the Battery

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4 replies [Last post]
Former Member
gainorc's picture
Potomac, MD
Joined: May 14th, 2002


1995 S420 LWB

I would like to disconnect the battery in an 95 S420 to see if the check engine light goes off. A tech ( not at a dealer) looked at the problem yesterday, could not find one and reset the computer.

He said he could not find any faults. However the the check engine light has returned today.

One earlier respondent said that disconnecting the battery could cause drivability problems.

Charles Gainor

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Former Member
Sokoloff's picture
Ocean Isle Beach, NC
Joined: March 29th, 1995


2003 SLK320
1983 240D

George Murphy may add more to this, but disconnecting the battery has apparently solved many unexplained electrical glitches in these cars. It worked for mine, but it also turned out that the battery was on its way out. The real cure was a new battery, although just last week my "Low Brake Fluid" warning light came on and the reservoir is as full as can be. It only came on that one time.

'99 E300TD



'59 220S cabriolet

'83 240D 348,500 miles original owner

'99 E300D 170,000 miles

'03 SLK320 27,500 miles

Tom Hanson's picture
Arrowhead Farms, CA
Joined: February 20th, 1997


1970 300SEL 6.3

Have your radio code handy. You'll need t.


Tom Hanson
Supervisor, Parts Operations
Mercedes-Benz Classic Center USA
949 598-4842 direct.

Prior MB cars: 2010 ML350 Bluetec, 2003 C320 Coupe, 1986 300SDL, 1971 300SEL 6.3, 1973 450SE, 1959 220S, 2011 C300

Wayne Halvarson's picture
Fairbanks, AK
Joined: December 9th, 1998


1997 S320 LWB
2002 C230

I am also curious, what if any engine / performance codes
should be recorded and restored when the battery is replaced?
The last battery I replaced died rather suddenly and I would
like to have the reprogramming information on hand should it
happen again. Thanks, Wayne.

Anonymous's picture

Hi chuckg i would have your car retested if check engine light came on their is a code in one of yourcontrol units hie scanner may not have been able to go beyond the engine diagnostic module.on your veh you also have a base module di module and aea module all can have fault codes.its important to know your system some hfm-sfi if battery dead to long can loose its idle adaptation some veh will need the steering angle sensor re inilalized ect some conponents will not .like Tom said have your radio code handy if you donot have a 9 volt cigar plug in adaptor.joeym

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