Bunk - did you test to see the bad ground?

I ask since I have been suffering the 1606, even as far back as 2020 when I jut swapped in a new module.

It happened again fall 2025. I went through relays and 2 used VVEL modules and even a brand new one. Nissan currently thinks I need a new main ECU after testing voltage at start, grounding, wiring issues, but your solution gives me hope that there’s an easy fix.

I remember testing the harness a while back and didnt find a bad ground. I had tried EVERYTHING possible - even went through 3 different modules. I did the ground to the bracket just for grins, and it only takes a minute to do... and it worked. It's only temporary until I finish moving next month, i still have work to do.

Thank you. My local Nissan dealer has had my car approaching 4 months. We’ve tried multiple VVELs, used and new. Relays. Tested ground, wiring harness, and cold crank voltage. They currently are awaiting another main ECU to show up - theory is that is the issue, but I’m curious to see if your grounding to the VVEL bracket is in fact the issue with P1606.

Give it a shot, its fast and easy. Make sure to do the ECU reset also. P1606 couldve been anything, but since i did try everything else short of messing with the VVELS themselves, im almost 100% sure that my issue was ground. Hasnt failed since I did the ground wire.

When I started having this problem, it would go away if it sat overnight, then it would come back, and progressively got worse. There might be a faulty pin that loses connection from vibration.