2018 Freightliner Cascadia DD15 - Forced Regen Fails and Stuck in 5MPH Derate

Question

I am stuck at a rest area and the truck keeps failing its parked regen about 10 minutes into the cycle. It gives me a 'Low Temperature for Regeneration' message on the dash even though the exhaust feels hot. The truck is currently in a 5MPH derate and I cannot clear the active codes with my basic scanner.

Tom Patel · Accepted Answer

The issue was a completely carbon-faced Hydrocarbon (HC) Doser valve and a failing DOC Inlet Temperature Sensor. I replaced the HC Doser (Part #A0004900500) and the sensor. After installation, I had to use DiagnosticLink 8.0 to perform an 'Aftertreatment Device Regeneration' and then a 'SCR Efficiently Test' to clear the 5MPH derate. Total parts cost was around $650 and it took about 2 hours including the forced burn.

Rachel Nguyen · Answer

This sounds like a typical HC Doser block. Before you buy parts, check the fuel line going to the doser valve. Often the tiny screen inside the fitting gets plugged with debris from the fuel system.

Sam Holloway · Answer

Check the DOC inlet and outlet pressure sensors. If the sensors are reading incorrectly, the MCM won't allow the regen to proceed for safety reasons. You really need DiagnosticLink software to see the actual temps.

Sarah Thompson · Answer

You need to check your 7th injector (Hydrocarbon doser). If it is clogged with carbon, it won't spray enough fuel to get the DOC inlet temps high enough to start the actual soot burn.

2018 Freightliner Cascadia DD15 - Forced Regen Fails and Stuck in 5MPH Derate

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