My W124 has a check engine light, and the LED of the on-board aka California diagnostics is solid lit and does not respond to the button being pressed.

I've checked pins 6, 7, 8, and 14 with my blink reader, all blink 1 for clear.

The engine is running smoothly, no weird noises, smells, or behavior. This morning when I started it cold (ambient around 35F), it started without difficulty but died as the revs were coming down from start to idle. Did that twice, third time no issue. Don't know if that could be related; CEL didn't come on til three (warm) starts later.

Was passiert hier?

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RIP:
2011 E350 BlueTEC, Schwartz 81k (totaled by uninsured drunk driver)
1964 Unimog 404.1 (wrongfully towed by the city)
1994 E320, Brilliantsilber 208k (transmission shuffled off after sudden catastrophic fluid loss)
1982 300D, Silberblau under a blue repaint 256k (sold for parts)
1995 E320 Polarweiss, 131k (sold for parts)
1995 E300D Polarweiss, 287k (totaled by drunk driver)

Somebody else just had that exact problem , perform a hard reset by disconnecting the diagnostic module and reconnecting power should behave normal afterwards, diag module behind dash to the left

Well, it seems to have cleared itself with more driving.

Mods, feel free to delete this thread.
Thanks, nulu!

__________________
RIP:
2011 E350 BlueTEC, Schwartz 81k (totaled by uninsured drunk driver)
1964 Unimog 404.1 (wrongfully towed by the city)
1994 E320, Brilliantsilber 208k (transmission shuffled off after sudden catastrophic fluid loss)
1982 300D, Silberblau under a blue repaint 256k (sold for parts)
1995 E320 Polarweiss, 131k (sold for parts)
1995 E300D Polarweiss, 287k (totaled by drunk driver)

okto, when was the Oxygen sensor replaced last? It's also possible that the EGR tube that runs behind the engine and connects to the intake manifold is blocked with carbon deposits.

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Fred Hoelzle