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 2008 Thomas EF Fault Code Woes
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Thomasfan89
Top Member

USA
1155 Posts

Posted - 04/07/2015 :  12:41:32 PM  Show Profile  Reply with Quote
We have a 2008 Thomas EF 6.7 Cummins ISB (EPA 07 Engine), Allison 2500, 61,XXX miles (almost all city driving). We've got a red STOP ENGINE light on, and the cluster is reading the following code: ECU 128 SID 68 FAIL 00. When we drive the bus, it won't go over 35 MPH. Engine sounds normal, no rough idle or anything like that. To me, it sounds like it needs a regen. Now here's the problem: from what I've gathered, this bus (and its twin) have had issues since day 1 with the emissions system. For example, it will not do a parked regen, and for all we know, it may not be doing highway regens when we take it out on a good long drive. We've never had a DPF light come on, nor hot exhaust light. When we go to check that code, I can't find information on SID 68 anywhere. Mechanic said in years past, a good highway drive usually clears the bus up for at least a little while. This time, that doesn't seem to be the case. He also thinks this code is a new one. Sadly, we don't have any Cummins software or diagnostic equipment other than a code scanner. Cummins dealer is telling us just drive it and it will clear itself out. Thomas dealer is saying call Cummins.

Has anyone had this problem before? I'm trying to save us a trip to Cummins (or worse yet, the Thomas dealer). Thanks in advance for the help guys!

-Greg

exmod110
Senior Member

150 Posts

Posted - 04/07/2015 :  2:00:06 PM  Show Profile  Visit exmod110's Homepage  Reply with Quote
Cummins has a free "limited ability" software that will let you read the code and give a description.. load it into ur diag laptop and use the cables you have already.

http://www.powerspec.cummins.com/site/home/download.htm
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krmvcs
Advanced Member

362 Posts

Posted - 04/08/2015 :  07:29:50 AM  Show Profile  Reply with Quote
i couldnt find it either in any of my fault lists. however i did find this on google.
a fault with a turbo related sensor would make some sense given that your speed it limited. sounds like the engine went into a derate mode. good luck.

http://www.justanswer.com/heavy-equipment/33h5d-cummins-getting-code-128-sid-68-00i-know-what-lost-power.html

-Ken-
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Thomasfan89
Top Member

USA
1155 Posts

Posted - 04/17/2015 :  07:04:22 AM  Show Profile  Reply with Quote
Thanks for the replies. Here's an update:

We caved in and took it to Cummins last Wednesday. Causes of all our headaches: cracked DPF, faulty DOC. Since the bus wouldn't regen, everything else was nice and full of carbon. It wasn't a cheap repair bill, but the bus is back in service now. It's true test will be when we run it this afternoon.

Now here's the question: should we have the twin to this bus inspected to try and prevent this type of meltdown on that one too? We're not really equipped to tear into this system here unless it really isn't that involved. So far this year, it hasn't thrown any Check Engine or Stop Engine lights, no current fault codes, but has the same history of refusing to regen. Any thoughts?

-Greg
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krmvcs
Advanced Member

362 Posts

Posted - 04/17/2015 :  07:15:01 AM  Show Profile  Reply with Quote
get cummins insite, and have the dpf removed and serviced periodically.

-Ken-
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