2017 C43 AMG - "Check Brake Pad Wear" indicator appears at vehicle start. Instrument cluster "BRAKE" indicator illuminated while driving. Visual inspection indicates brake pads are not worn though. Inspected wear sensors, they are intact, plugged in. Two conductors to the sensor, ohmed them out, they have no resistance. Brake fluid level is good also.

Anyone know what's going on?

 

Which brake pads and sensor did you check? I believe the C43 like the C63 has a front and rear sensor. The rear pads tend to wear first at least on the C63. I just had to replace my C63's rear pads at 17k miles after the warning came on in the dash. The sensor is just a wire loop essentially that wears through once the pads are worn, so it's no longer a closed circuit. Also keep in mind the outer and inner pads can wear at different rates.

 

Both front and rear, the sensor is on inboard pad passenger side only. Plenty of pad wear left at all four wheels, both inboard and outboard pads. Both sensors are totally enclosed in pad material, not touched by the rotor. I'm thinkin something else is going on, or a malfunction with the indicator.

 

You can try a brake sensor bypass to rule out the sensors. If you still get a warning after bypassing the sensors then you know the problem is somewhere else.

 

I found a post (How to disable the OEM brake wear sensor?) where the OP found the sensor wire abraded where it enters the body of the vehicle and broke the circuit.

This is the wire harness leading away from where the sensor plugs into the harness bolted to the caliper and into the body/chassis of the vehicle. I'll look for this possibility tomorrow.