CUSTOMER CONCERN A motor-like noise runs continuously under the hood and the Active Hydraulic Booster stores DTC C1237 for the primary pressure-sensor signal. CAUSE Hydraulic pressure data did not respond while HPU battery feeds at pins 1, 2, and 3 and grounds at pins 25 and 26 were present, confirming an internal Hydraulic Power Unit failure. CORRECTION Remove and replace the failed Hydraulic Power Unit, bleed the brake system, perform pressure-sensor calibration and require

CUSTOMER CONCERN Customer requests diagnosis of hydraulic power unit primary-pressure sensor signal DTC C1237. CAUSE Confirmed internal failure of the hydraulic power unit caused improper pressure or an invalid internal pressure-sensor signal and set DTC C1237. CORRECTION Remove and replace the hydraulic power unit.