I have a 2013 Lexus ES, and I recently experienced trouble starting the car. The car was showing code P1604. I had to get a new battery and alternator. After re-checking the car, I am still getting the code P1604. Does anyone know what might be the reason for this?

 

Did you reset the code after you replaced the alternator/battery?

 

I assume it is ES350? There is a million things than can cause P1604. The service manual section on P1604 is 57 pages long (see below). If you want to diagnose it yourself you would need to get familiar with Techstream - otherwise bring it to a qualified shop or a dealer (not a parts cannon mechanic).

What are you symptoms besides P1604? Have you tried to switch to a different gas station and run through at least one more full tank of gas?