Cleaning the front sensors might not fix it. There is a grooved ring in the hub that the sensor is reading. If that grooved ring (looks kinda like a geared ring) is full of junk, the sensors may not be able to read it correctly. Pull the sensor and put a compressed air probe in the hole to the senso-ring and rotate the brake rotor whilst blowing the air - that might just fix it.

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There is a very fine line between "hobby" and "mental illness."
FrankenBenz: '87 560SEC with an '02 cammed LS6 and custom 4L60E.
Bling: '87 560SEC, ported/polished, lowered
Lisa: '87 560SEL, lowered