My Mercedes shows a dashboard warning for a bulb out, but all lights seem fine — what’s causing this?

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My Mercedes shows a dashboard warning for a bulb out, but all lights seem fine — what’s causing this?

My Mercedes E-Class W211 shows a bulb out warning on the dashboard, but when I check, all the exterior lights appear to be working. This happens on and off, especially when I start the car in the morning. Could this be caused by voltage fluctuation, a bad bulb socket, o r sensor fault? Is this a common issue in imported Mercedes cars in Pakistan?

Talha Kyanii asked on 11 Oct 2025 11:03:33 am

1 Answer

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Gari Master - on 11 Oct 2025 11:05:06 am

This is a very common issue in imported Mercedes-Benz cars in Pakistan, especially older models like the W211 E-Class.

Possible causes:

Slight voltage difference: The car’s computer constantly monitors the resistance and voltage of bulbs. A bulb that’s aging, even if still working, may trigger a warning.

Poor-quality o r non-OEM bulbs: Locally available bulbs may draw slightly different current, confusing the bulb monitoring system.

Loose o r corroded bulb sockets: Dust, rust, o r poor contact can cause intermittent readings, especially during startup o r vibration.

CAN-BUS sensitivity: Mercedes uses a CAN-BUS system that requires specific electrical tolerances. Any deviation, even slight, can cause false errors.

What to do:

Check each light with the car running to see if any flicker o r appear dim.

Use diagnostic tools like STAR o r a good OBD-II scanner to confirm which circuit is triggering the error.

Replace with CAN-BUS compatible o r original bulbs to avoid warnings.

Clean o r replace corroded bulb sockets.