2011 Nissan Murano SV 3.5L Transmission Codes P1715, P1778, P0745, P0865 - Speed Sensor Sludge Cause?

I recently purchased a 2011 Nissan Murano SV with the 3.5L V6 engine and front-wheel drive. After bringing it to a Nissan dealership, I was given several diagnostic trouble codes: P1715 (Input Pulley Speed), P0745 (Pressure Control Solenoid A), P1778 (Step Motor Current in ECM and TCM), and P0868 (Fluid Pressure Low Current). I have already removed and inspected the valve body, which was recently replaced. Additionally, I replaced the input speed sensor and discovered a thick layer of sludge with fine metallic particles throughout its internal components. This leads me to suspect that the sludge may be directly causing the P1715 code. Could this simple issue—faulty or contaminated sensor—be responsible for all these related transmission codes? I’ve researched extensively, but I’m hesitant to spend $160 on transmission fluid replacement just to verify if it’s a sensor failure. Would a defective speed sensor be sufficient to trigger multiple codes like P1715, P0745, and P1778? The vehicle accelerates smoothly up to 20 mph, after which the RPM gauge begins to rise uncontrollably—no warning lights, no unusual noises or shifting issues. The behavior is consistent but concerning. Any insights or expert opinions on this would be greatly appreciated.