SPN 3241


Registered User
Mar 20, 2023
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Oak Park Ca.
I recently acquired a 2010Freightliner step van Cummins 6.7 not running. two batteries and a set of starter brushes took care of the not running. It starts and runs fine and a short trip around the block the trans seems to be working fine.

Problem is that I need to get it smogged and with the SPN 3241 that is not possible. I bought a diesel friendly scan tool a couple of weeks ago and what it is saying is that the 3241 is a hard code. There is a line and under the line it says is FMI 13 out of sinc.

What I have done so far is:

Completely clean the EGR system. The valve has been replaced at some point, it is green not engine red. I cleaned the valve with a small wire brush and confirmed that it works smoothly, and soaked all the other parts in carb cleaner till they sparkled. did not change a thing.

Somewhere in searching the 3241 code a question of exhaust gas temperature came up. I found that if you let it idle for 3-4 minutes the CEL will start flashing and about a minute later the engine shuts down. Somewhere I read that when the exhaust gets too hot this is what happens. So I started it up and felt the exhaust temperature and noticed that when the outlet temp started rising the engine would shut down. In my blissful ignorance I added 2+2 and came up with 17. Figured OK bad temp sensor so I replaced all three in the DPF/CAT assembly $580 some later no change.

I then discovered that at idle the scan tool shows 0 turbo pressure and at high idle it shows 4.3. So I disconnected both ends of the turbo started it and the turbo is spinning at idle, no noises and plenty of flow at idle. All the air it is moving has to be going somewhere so my assumption is that the pressure sensor might be bad. I don't know where it is or what it looks like and am through buying expensive Cummins parts until I can find answers.

I did take the DPF/CAT apart just because it is there and you can see light through both assemblies. For whatever it is worth it does not use blue def, nor does it have a diesel injector in it. I am not entirely sure what those are all about only that I have encountered both doing internet searches.

There is a stainless line that screws in to the dead space between the DPF and the CAT and another that screws in downstream of the cat. Those two lines connect to a plastic piece that has wires to it. I do not know what it is or what it is supposed to do so cannot test it.

Just as an FYI I have been working on automobiles for 60+ years but know nothing about diesels. I have posted this on several diesel forums, I am posting here now because after trying to join here for over a week I finally managed to do it. I was beginning to believe that my reputation got out and I was being blackballed. No one else has any answers hopefully you do.

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