I just changed the spark plugs on a 1997 SL320 and the engine sputtered a couple of times when I started it for the first time. This turned on the "Check Engine" light and it stays on now even though the engine runs smooth. Does anyone know how to reset this light?

Thanks,
Hank
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SEXFACTOR

 

does disconnecting and reconnecting the engine control unit does it?

 

Great idea sleepwalker. That took care of the problem. Thanks a lot.

For the record:
To reset the "Check Engine" light (and probably lots of other stuff too) on a 1997 SL320, you can remove the four harnesses that run from the engine into the ECU. According to my Emissions Control sticker this procedure probably works on the C280, C36, and S320 as well.

If you have questions on how to do this please email me at: hankrouth@hotmail.com
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Red Head Girl Live

 

even on new S-Class. S280, S320, S500, S600.

the ME control unit got no memory if the power supply is interrupted.

 

Disconnecting the battery has to be safer than disconnecting and reconnecting four "live" harness wires leading into the ECU, wouldn't you say?

 

yes. and easier too.

 

If you don't have the radio code, removing the ECU wires resets the "Check Engine" light without resetting the radio.
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LovelyWendie99

 

It's a lot easier to get the radio code from a dealer than it is to replace the ECU.

 

Assuming you know the radio code and diconnect the battery. How long do you have to wait to reconnect the battery and does the "Check engine light" goes off after the reconnection of the battery? Thanks

 

Disconnect both cables. Without letting either cable touch anything else, touch them together for about 10 seconds. The ECU memory will be cleared of the trouble code and the CEL will be reset immediately. Then, reconnect the cables to the battery.