pooler00

Replace the oil cooler/oil filter housing on my 2015 JK 3.6. The vehicle runs great for about 10 minutes then I get a check engine light. The first code was p1618 (When the Powertrain Control Module (PCM) recognizes the Primary 5-Volt Supply circuit voltage is varying too much too quickly.). I cleared the code, drove again then I got a po642.

I took everything apart after not having any luck figuring this out, put it all back together and I am still getting this codes. Im not sure what direction to take at this point.

Thanks for your help!!

pooler00

I will add that the first time I started the vehicle I forgot to plug in the IAT. I cleared the codes and plugged it back in but still get codes again.

Tricky_Dick

Since both codes are dealing with the 5v supply I would start to look for a short or chaffing wires in and around the oil cooler.

take a look at the below wiring diagram and you can see that oil pressure sensor shares a common 5v supply with throttle body, which you had to also take off to get to that cooler, and the crank position sensor.

here are the other possible causes to make sure you chase down…

XJRefugee

nice input there Tricky - gives the guy a place to start

resharp001

Any update on this? I'm just generally curious cuz I've never had to deal with any issue with the 5v circuit. I have a hard time thinking that on a 2015 we're seeing an issue with chaffing wires, or other similar physical issues, which could surely be common on an older vehicle. I was wondering if this could come back to that initial start without the IAC plugging in. I know the codes were cleared but did you ever actually just disconnect the battery and leave it for a bit? Have you been able to find the source of the issue in the time since the original post?