Code P0340 - stalls when engine is warmed up?

Tiny
WANGO78
  • MEMBER
  • 2004 INFINITI FX35
  • 3.5L
  • V6
  • 2WD
  • AUTOMATIC
  • 135,000 MILES
I had my automatic transmission rebuilt at a local AAMCO 3 months ago.

My car was running okay, but I felt some vibration around 2,200 RPMs intermittently since then.

Since the mechanic told me the new transmission might need ‘break-in-period’, I just took it as-is.

After a week or so, however, it started stalling when the engine temp went up to the normal working temperature and it was throwing CEL, vdc off, slip (P0340 per scan)

On top of vibration issue, I hear squealing noise from belt area when P0340 just comes on.

I replaced 2 cam shaft position sensors and a crankshaft position sensor.

In order to check whether any of the wires had an issue, I tried to start the car with each sensor disconnected.

Car could start without cam sensors but the p0340 code was pulled right away. (When sensors were plugged, p0340 came on after the temp went up)

Car could not start without crank sensor at all. (When connected, P0340 came on when the temperature went up)

Thus, I assumed that all the wirings are at least sending/receiving signals.

Battery is new, and I replaced MAF.

What should I check or replace now?

Alternator signal needs to be checked with oscilloscope scanner like some experts say on YouTube.

Or do I have to replace crankshaft sensor with genuine part or the one that does not need to be relearned or programmed?

Any advice will be appreciated!
Monday, February 20th, 2023 AT 5:47 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,170 POSTS
Hi,

The code is related to a camshaft position sensor, but I'm not sure why it is making a noise. Is the noise loud enough to record and upload for me to hear?

I'm not sure where you got the new sensors, but I have had a lot of issues with the new aftermarket parts being defective.

I attached a simple test for the sensor itself below. Take a look and let me know if you are comfortable performing them.

Next, the alternator is easy to test. You only need a voltmeter or multimeter. Follow the directions in this link and let me know the results:

https://www.2carpros.com/articles/how-to-check-a-car-alternator

When you test the alternator, you are checking a DC circuit. Just as a test, turn the meter to AC and check for power at the battery. It should remain at 0. If there is any variation, replace the alternator. Chances are you have a diode failing.

Let me know what you find.

Joe

See pics below.
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Monday, February 20th, 2023 AT 7:24 PM
Tiny
WANGO78
  • MEMBER
  • 2 POSTS
Hi Jacob. Thank you very much for taking care of my case. Let me work on those projects and get back to you soon.

BTW once p0340 is turned on, the car doesn’t stall unless the engine cools down to cold temperature and gets warmed up again. Of course, the engine vibrates intermittently while p0340 is triggered.

It’s very subtle because of traffic and road noise on top of fx35’s loud exhaust sound. Let me try to record in a quiet suburban area later. Thank you.
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Tuesday, February 21st, 2023 AT 11:55 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,170 POSTS
Hi,

First, I'm happy to help, so no problem whatsoever. The funny thing about the sound is how and when it happens. When steel gets hot, it expands. When you removed the cam sensor, was it in good condition and not showing any evidence of possible damage?

I ask because I'm wondering if something is expanding and rubbing when it gets hot. It's only a theory.

If possible, get that recorded. Hopefully, it will be something I can recognize.

Take care,

Joe
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Wednesday, February 22nd, 2023 AT 7:06 PM

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