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Replacing K40 Relay in Engine Compartment Fuse Box

Model: Mercedes Classe E W210 - Years 1995-2002
Part: Checks and maintenance

If you are experiencing engine starting issues and warning lights on the dashboard, one possible cause is a faulty K40 relay located in the fuse box in the engine compartment, on the passenger side, near the strut tower. Once you remove the cover, you can easily identify this relay; pull it out from its socket and insert the new one. If the problem does not resolve, proceed to the next step: remove the fuse box and check the solder joints on the underlying circuit board, and re-solder them if necessary.

Updated on 10 February 2026 by ScegliAuto

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