P033D
valley plate
knock sensors

I have a 2018 GX460 with 100 K miles and have a fault code P033D #4. I'm in the process of removing the intake manifold to access the valley area to get to the sensors.
I have a few questions for the group. Due to the amount of disassembly to access the valley, should I?

• Any tips on disconnecting the wire harness from the intake that's at the back of the engine.
• Replace all four knock sensors
• Replace the knock sensor harness
• Remove and reseal the valley plate even though I have no signs of coolant leaking
• Any other parts change recommendations as precautionary since I am doing this job