P0340 Cam Position Sensor Code when hot

[jeffhoward001]

Hi All -

 

Getting ready to take our Journey to the dealer, but have a weird issue and wanted to run it by fellow gear heads. Journey runs fine, except we went on a long road trip from Arizona to Oregon. Lots of hot weather and long mountain grades.

 

We've done the trip several times before, but this time the Journey had problems when the outside air temp was 90's+ on steep grades. We were loaded down pretty heavy which I'm sure wasn't helping.

 

So during the hill-climbs, after having your foot into it for a while, the CEL came on and trans went into limp. Pulled the codes at AutoZone and they said it was a P0340 Cam Position Sensor Signal Intermittent issue. It was 102 degrees out when this happened so we chalked it up to the heat and the hills and kept going.

 

We made it 100's of more miles until it happened again in similar conditions... Hot outside air temp, big mountain pass. However this time I was watching the gauges and noticed the oil temp max out at 275 when the CEL came on.

 

So is the high temp of the oil putting pressure on a cam position sensor that's already on its way out, or is there something else going on? The oils has always ran hot in our Journey but 275 is pretty hot (but within spec for blended synthetic which is what we use).

 

Any thoughts?

 

[John/Horace]

Which engine, milage on vehicle would be useful. Still original battery ? Sensors sensitive to voltage in system.

 

 

[John/Horace]

Checking for signs of heat or mice damage to wiring harness going to cam sensors could be first step. Unplug  sensors and look for corrosion on plug pins, reseat each with dielectric grease. If it was really a bad sensor I think you would have on going drive ability issues. 

 

The 2.4 seem to have cps crank position issues sometimes, a flaky crank sensor could also possibly trigger this code. Failed cps means tow truck and it’s fairly cheap part. I don’t like throwing parts at a car...but known wear items I tend to replace before getting stuck, I also do some long trips and want confidence in my vehicles.

Even low voltage from a tired original  battery can do weird things. 
Vague diagnosis with laundry list of possibilities not really useful IMO, and normally not cheap. I would eliminate some of the wear items first, then pay for professional help second.

[jeffhoward001]

Hi All - 3.6L engine, 110K miles, no the battery has been replaced. If it was the battery, I would guess it would happen more that just when the oil gets hot.

 

Does 275 seem too hot for oil?

 

John - I'll check the wiring harness.

 

[John/Horace]

Extreme heat kills batteries faster than cold just mentioning it.  Flaky   sensor-issues sometimes tied to .battery.

 

I have found that  engine  oil usually closely follows glycol temp , usually a little lower at all times. So 275 is high, full synthetic claims more protection for extreme heat, that is one option.
There are often other thermostat choices for vehicles other than factory default unit. Since it’s the engine glycol cooling your  oil in the heat exchanger you could easily lower that 275 oil temp with a cooler setting of thermostat.

Thermostat comes with housing, it’s cheap and easy to change.

 

Last is quote from the google...they think 275 is too much as well.

 

 

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Featured snippet from the web

A quality conventional motor oil will tolerate oil sump temperatures of up to 250 degrees, but starts breaking down over 275 degrees. The traditional approach is to try to hold oil temperatures between 230 and 260 degrees.

[jeffhoward001]

Haha, we did the same oil research on Google. Turns out this is a well-documented issue on all FCA motors that use the the heat-exchanger built into the coolant system. I found the same complaints for the Eco Diesel and 3.6L RAM 1500's and Durango's. For the RAM & Durango guys, they're all towing well below the started GVRW, so this is just an Achilles Heel of the heat-exchanger unfortunately

 

In fact after some additional reading, sound like the original intent of the design was quite the opposite: they were trying to better regulate the LOW temp of the oil in cooler climates. So I'm an edge-case with our Journey hitting the mountains in 90+ degree heat with a heavy load.

 

The biggest bummer is you could resolve this issue with a cheap $100 universal oil cooler if the 3.6L didn't use the canless oil filter

 

[John/Horace]

I’ve done more than google research with the heat exchanger; I replaced mine when it leaked two years ago.

There is a lot of pressure from pumping cold oil, there were failures of o ring seals, mine did. Sticking to 5w20 synthetic is a good idea in the north (although mine failed with 5w20 Castro Edge in not extreme cold at 90k miles).

 

The  quest for fuel economy means heating the oil quicker and more efficiently. Location of heat exchanger makes it a bear to change.

 

Just grabbing a thermostat housing with a colder thermostat Installed off the shelf may not be that easy. Rockauto shows only the factory 93C or 203F unit offered in six different brands. 

Pickup 3.6’s use an aluminum thermostat housing and thermostat can be popped out of housing and probably changed but itself. It’s the same engine so may be possible to install it on a journey. Transverse versus in-line engine mountings. Search the Ram forums for what the DIY folks are doing, or charger people.

 

https://www.rippmods.com/collections/maintenance-replacement-parts/products/2012-2016-pentastar-180-deg-thermostat

 

Edited May 15, 2020 by John/Horace

[jeffhoward001]

So I'm pretty sure I figured this out after connecting a few dots.  Now that we're back up in Oregon where its considerably colder than Arizona, we noticed the heater is hardly working.  I haven't 100% confirmed, but I suspect the hose that comes out of the back of the oil cooler likely goes through the firewall to the heater core.  This was mentioned in another thread about someone complaining that their heater wasn't working.

 

So if that is true, then this all makes sense.  The heat exchanger in the oil cooler is clogged up, so little to no coolant is flowing through the oil cooler (thus making the oil hot) and not allowing the heater core to work properly.  I would love to see a diagram of the heating/cooling system, but haven't been able to find a good one to confirm.  I would follow the hose on the Journey, but it's buried under the intake manifold :-|

[John/Horace]

The plate heat exchanger has highly treated glycol running through it. Really no reason for it to be plugged up, a chemical descaler might help marginally.  There are problems with plastic part of het exchanger cracking and o ring failures.

The  heater core has supply and return hoses running through firewall, like the a/c evaporator does. If one  hose is hot and no heat in cabin more likely one of the dash actuator switches not working.

 

If your dash cluster is now showing reasonable  engine temperature I think flow is ok. If heat is coming and going, glycol level or thermostat could be problem.