2018 Kenworth T680 - Cummins X15 Fault Code 2688 Derating

Question

My X15 is throwing code 2688 and I am losing power on grades. The dash is showing a soot level high warning even though I just did a parked regen two days ago. I am worried the DPF is plugged or there is a sensor sensor issue causing the ECM to see incorrect pressure.

Luis Hernandez · Accepted Answer

The issue was a cracked DPF substrate and a failed Aftertreatment Differential Pressure Sensor (Part #4307166). We found the sensor was biased by 0.2 psi at key-on engine-off. Replaced the sensor, cleaned the pressure tubes with shop air, and installed a Reman DPF. Forced a deep soot reset via Insite and the truck has been running clean for 5,000 miles now. Cost was roughly $2,800 for parts and labor.

torque_terry · Answer

Check your differential pressure sensor tubes for any moisture or soot buildup. If the tubes are restricted or leaking, it will give the ECM a false pressure reading even if the filter is actually clean.

fleet_chief_42 · Answer

Run a snap acceleration test and monitor the Delta P sensor voltage. If it jumps immediately to over 4.0 volts, the filter is likely face-plugged and needs professional aqueous cleaning or replacement.

Megan Rivera · Answer

You need to look at your SCR crystalization and EGR valve. If the EGR is sticking open, it will produce excessive soot that the DPF cannot keep up with, leading to frequent 2688 codes despite successful regens.

2018 Kenworth T680 - Cummins X15 Fault Code 2688 Derating

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