luiselorenz1

Mercedes E Klasse ABS Fault

My 2005 Mercedes E Klasse with a diesel engine has an ABS lamp that stays on, and I'm having traction problems. The diagnostic points to a speed signal fault at 274877 km. Could this be a defective control unit? Has anyone seen this before? Trying to understand the potential repair cost, maybe around 1000€.

4 comment(s)

The speed signal fault on the E Klasse is a known issue. A defective control unit is a plausible cause, especially regarding the signal input from the transmission speed sensor. Before replacing the unit, check the sensor and its wiring for damage, corrosion, or loose connections. A faulty sensor can appear as a control unit malfunction.

Thanks for the advice. How do I test the sensor to see if it's sending the correct signal? I'm not sure how to check the transmission speed sensor or where it is located. Any pointers?

Due to the system's complexity and the chance of misdiagnosis, a qualified technician should do a diagnostic evaluation. Replacing the sensor without confirming the control unit's functionality could be a waste. Based on the symptoms, a control unit replacement might be needed, especially if the diagnostic indicates an internal fault. You could try to replace the sensor, but you will likely need a workshop.

I took your advice and went to a workshop. The ABS control unit was faulty, like the diagnostic showed. The speed sensor input wasn't being processed correctly. The replacement cost around 1000€. Thanks for the help!

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