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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 54022
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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C300: P2123 - ESP & Cruise not functioning almost zero acceleratio

Customer Question

P2123 - ESP & Cruise not functioning almost zero acceleration response. Clear codes, cycle ignition and it works fine for about three throttle sweeps. Any history with this issue?
Submitted: 2 years ago.
Category: Mercedes
Expert:  Marty replied 2 years ago.
Hi, a P2123 is a fault code for the accelerator pedal sensor. If you have Star Diagnosis you can go into the ECU and monitor the actual values of the potentiometer. To be quite honest, this code is usually caused by a faulty accelerator pedal. If you are unable to test the pedal I would just swap it out with a new one. The pedal is plug and play. I've attached the test steps below. Just copy and paste the link.
Let me know if you have any questions.