Nissan Versa Forums banner

P0643 hard fault on code reader, check engine light, and limp mode

285 Views 7 Replies 4 Participants Last post by  amc49

I have a 2016 Nissan Versa S with manual transmission and basically power NOTHING. :-D Last night my car went into limp mode with a check engine light and a traction control light. Initially I was seeing code P0643 as active, with P0340 (camshaft position sensor) as pending. To start with cheapest option I replaced both camshaft position sensors. That fault went away but I still have P0643, it won't clear, and car remains in limp mode.

I know this fault refers to:

ECM supplies a voltage of 5.0 V to some of the sensors systematically divided into 2 groups, respectively.
Accordingly, when a short circuit develops in a sensor power source, a malfunction may occur simultaneously in the sensors belonging to the same group as the shorted-circuit sensor.
Sensor power supply 1

So my fault appears to be on sensor power supply 1. I don't know what components are on this bank. Does anyone know exactly which sensors are on Power Supply 1 on a 2016 Versa so I can start checking the connectors and maybe voltage too?

If anyone has any experience with P0643 and can help guide me to a possible fix I would be grateful. I don't have a lot of one and I really can't afford a mechanic right now so any help I could get would be much appreciated. I am reasonably mechanically inclined so I should be able to follow basic instructions.

1 - 8 of 8 Posts
That one could get ugly, it says the ref voltage is too high. Check all grounds and especially at ECM, because it can be ECM problem or 12 volt has shorted somewhere in harness across to VREF to make the usual reference 5 volt too high.
  • Like
Reactions: 1
Go to and download the Factory Service Manual, if you haven't done so. It is FREE to download.
It may be for MY 2014, but not much would have changed between that and 2016.
There are specific procedures in Section EC about diagnosing P0643.
As @amc49 suggested, I'd look for signs of chafed or rodent chewed wiring. Corroded ground lugs can also be an issue.

Was there any problems at all leading up to this?
Wow guys thanks for the responses so quickly! I want to answer a few questions asked of me:
1) there is no apparent sign of rodents chewing on my wires that I can see outright. I also live in an arid climate so we typically don’t deal with a lot of corrosion here.
2) the car was driving perfectly fine prior to this. I was literally just coasting to a stop sign in neutral when it happened. The car has never had a single issue. It has 83K miles on it.

I will definitely download the service manual! That will help. My other question to you all: where exactly is the ECU/ECM located so I can start tracing wires better? I don’t know exactly where it is located to even start looking for signs of chafing or broken wires that would suggest a short.
You might consider the camshaft sensors as they were reporting trouble. The connectors and first few inches of wiring.

Service manual will tell you where ECM is. And bear in mind sending any power into ECM at low power wires can easily blow it out, disconnect the main harness when testing harness.
Ok, so I started with the F11 connector and checked pins 72, 74, 78. Manual said should they should have 5V. NONE of them had any power at all. 0V. What do you make of this? I had the ignition to ON. The next steps are to check for short to power or short to ground between the different sensor connectors but I am getting 0V to those pins what’s the point?
Connector to test like that must be connected to computer and if still getting same then wrong connector would be first guess. There is also the issue of meter reading skills.
1 - 8 of 8 Posts