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Automotive HD/Fleet Forum

Professional automotive forum for discussion of heavy-duty trucks, buses and other on- and off-road equipment, and maintenance of automotive fleet vehicles. Discussion topics include fuels and lubricants, hydraulics, performance, on-board diagnostics, powertrain, power distribution, anti-lock braking and stability control systems, and best practices as they relate to heavy duty and fleet maintenance. This forum is for experienced automotive repair professionals only, membership required.

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Recent Automotive Discussions in the Automotive HD/Fleet Forum

Cummins Regeant Quality
08/03/2026 in the HD/Fleet Forum
Hello all and happy Monday, Working on a DEF derate problem on a Cummins ISB ESN [...] in a 2012 FL M2 with 189K miles. It was towed in for a derate, CEL and stop engine light. The Active DTCs were: 3543- NOX limits exceeded due to insufficient regeant qu...
cummins 15b 17 ?
07/30/2026 in the HD/Fleet Forum
this is a 6 cylinder in business class freightliner hp pump broke 3 teeth off pump, 1 off drive gear. tag is gone off motor . Only worked on a few of these motors ,normal or unusual brake teeth on drive and pump . What could have caused it ? thanks.
2017 Allison 2200RS troubleshooting
07/27/2026 in the HD/Fleet Forum
I'm trying to wrap my head around this- the trouble code is P0776, PSC2 stuck off. The symptom is that on the 3-4 upshift the truck drops to neutral and sets the P0776 My investigation lead to taking the pan down and listening. All solenoids make an audib...
2007 dt
07/25/2026 in the HD/Fleet Forum
I have an 2007 International 7400 with a Maxxforce DT. The engine when hot would intermittent misfire on half or some cylinders with no misfire codes So i put a scope on the cam sensor and i could also see the injector firing voltage and i noticed that th...
2018 Cummins ISb
07/17/2026 in the HD/Fleet Forum
We have a Cummins in a freightliner m2 that some times shifts into neutral or down shifts and you have to turn it off then restart to go again the codes it has is 3131 for the engine and code p0725 in the transmission tcm. Cummins Quick Serve is saying 31...

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