I agree with Jim - he has a great website with a wealth of information. Much of it exactly applies to your car since they are both w140 series vehicles. You should read about the diagnostic systems and how they are used.

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Daily Driver: 02 E430 4MATIC
In the family: '03 E500 // '04 ML500 // 64 220SE

I think this might be something worth having for a W140.

The mechanic I went to this summer told me the W140 (which includes the 600SEL) has 32 or 33 fault codes. It is a complex automobile. The W126 I think he said has just 10.

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1991 560 SEC AMG, 199k <---- 300 hp 10:1 ECE euro HV ...

1995 E 420, 170k "The Red Plum" (sold)

2015 BMW 535i xdrive awd Stage 1 DINAN, 6k, <----364 hp

1967 Mercury Cougar, 49k

2013 Jaguar XF, 20k <----340 hp Supercharged, All Wheel Drive (sold)

If the car is a '94 or earlier, the LED+SW combo should be there. It isn't a 'scanner' but it will read the Diag Module and give you an idea of what may be wrong.

If you are fortunate enough to have a scanner, then it is absolutely a great diagnostic tool.

One of the BEST ever made is the AST Retreiver which, unfortunately, is no longer being made. AST went to a PC based system. To me, that was a step backwards since you need to "drag" a laptop to the car in order to read codes. Seems like an overkill.

The "Retreiver" is self-contained system that is easy to use and gives "mercedes" type DTC explanations. Also could do LIVE data.

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Regards . . . . JimF
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'94 S500 Cpe

Visit my Mercedes Web Page

The MSRP for the V12 1992 600SEL was $127,800

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1991 560 SEC AMG, 199k <---- 300 hp 10:1 ECE euro HV ...

1995 E 420, 170k "The Red Plum" (sold)

2015 BMW 535i xdrive awd Stage 1 DINAN, 6k, <----364 hp

1967 Mercury Cougar, 49k

2013 Jaguar XF, 20k <----340 hp Supercharged, All Wheel Drive (sold)

Yea it also shocked me when i looked up the original price on the 92 s600.

The tool that I sell will allow you to read codes from the rest of the systems (not just the diagnostic module). My tool can't do live data (obviously) - but being able to read codes from the fuel injection, engine management, and other ancillary systems can provide you with a much better picture of why the "Check Engine" light is on.

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Daily Driver: 02 E430 4MATIC
In the family: '03 E500 // '04 ML500 // 64 220SE

Here is an older thread with additional code reader info.

Reading Codes

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GeneN
Charlotte, NC
1994 C280 135K