2018 Freightliner Cascadia DD15 - Forced Regen Fails at 60% with Code SPN 3216 FMI 20

Question

My Cascadia keeps falling into a derate after about 2 hours of driving. I try to run a parked regen via ServiceLink, but it gets about halfway through and then kicks out with a low temperature error. The DOC inlet temperature doesn't seem to be climbing high enough to sustain the burn.

torque_terry · Accepted Answer

The issue was a completely carbon-baked Hydrocarbon (HC) Doser block. While I replaced the injector nozzle, the actual port in the exhaust manifold was 90% blocked with hard carbon. I had to remove the doser block, drill out the carbon passage with a 1/4 inch bit, and reinstall it with a new gasket (Part # A0004901541). Once the passage was clear, DOC inlet temps hit 1100F immediately and the regen completed. Total cost was $45 for the gasket and about 2 hours of labor.

Luis Hernandez · Answer

Look at your DOC inlet temps on the graph. If they are stalling out around 400-500 degrees, your DOC might be face-plugged or the catalyst is dead. Also, check for a leaking EGR valve that could be dumping cold air into the mix.

Kevin Tran · Answer

You need to perform a low-pressure fuel system test. If your fuel pump isn't maintaining at least 65 psi during the regen cycle, the doser valve won't have enough pressure to spray a proper mist into the exhaust stream.

Sarah Thompson · Answer

Check your Delta P sensor tubes for any soot buildup or moisture. If the sensor is getting a lazy reading, the MCM won't command enough fuel to the doser to hit the target DOC temps.

2018 Freightliner Cascadia DD15 - Forced Regen Fails at 60% with Code SPN 3216 FMI 20

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