Here's an update on my original posting regarding the Check Engine Electronics error message. The message persisted for about 3-4 days. I took off the gas cap and wiped the gasket. I didn't see any dirt come off on to the towel.

The message cleared itself a about 2 days later and it's been off for about 3 days.

A few others had similar experiences with cleaning the gas cap. I don't know if cleaning the cap or even just removing and resealing it had anything to do with clearing the message.

I'll post another message on this topic if the problem returns. Thanks to all for your suggestions.

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Dave

1998 E320
2001 SLK320
2000 Lexus RX300