Car was throwing knock sensor codes P0325 and P0330. Check engine light on. Car radio intermittently goes off then comes back on and when that happens dash lights will sort of flicker and if headlights are on, they will turn off then comes right back on. Replaced both sensors and wiring harness. Found a rats nest underneath the intake manifold. After replacing sensors and harness, codes are still there but with them are now P0171 and P0420.
I would start by looking at all the wiring at and around the area you found the nest. Then look around other areas specifically around the ECM wiring harness. I think the P0171 is being caused by an intake leak and at the same time influencing the P0420 code. I have added the code information below.
Lexus Code P0325 & P0330 Diagnostic Procedure
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Lexus Code P0171 & P0172 Diagnostic Procedure1999-lexus-es330-codes-P0171-P0172
Lexus Code P0420 Diagnostic Procedure1999-lexus-es330-codes-P0420