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mikkhh

How does thst "dpf keep warm" cycle affect fuel consumption and reliability?

There has to be usage of more fuel to make more heat and also to get higher coolant temperatures faster injection timing gets advanced so more heat stays in engine shortening the lifespan of oil and internals.

Another misconception is that all and newer diesels smoke and the cans themselves are there to take care of the black smoke. That is not correct, modern diesel engine even without any cans should not produce any visible smoke at all! If it is then it is faulty, that is it. If the engine is not running right then the cans will get "plugged up" quite fast.

You need to get the engine running properly whether or not you decide to mandate'd it.

Have you cleaned the egr cooler? Egr piping? Visually inspected delta-p sensor, IMAP, back pressure sensor for carbon/soot plugging?

Pressure sensors can get worn and start to read incorrectly. It is very very common for IMAP, back pressure sensor, egr delta p, dpf differential pressure sensor to read correct value with engine off at that case 0, but when there is engine running and pressure the pressure scale is off. IMAP and back pressure sensor are the most important ones, considering that you have many trucks there just buy new ORIGINAL IMAP and back pressure sensor and compare the readings. If they were ok then keep sensors as spare. Constant regens can be due to dpf differential sensor readings being off.

3 year old 140 000 mile mx13 paccar had worn out IMAP, that caused all sorts of regen and scr issues. Truck went to official dealer for issues, but they looked up fault codes for dpf and scr - replaced nox sensors etc with no help... There was no fault code for IMAP, but the sensor was plugged and when it is plugged with soot then it is time to replace, official repair guidelines also tell that when sensor is plugged do not attempt to clean, just replace.

Pull the sensors and post pictures here for review if you do not want to "parts cannon" repair.

I had a 2.0tdi Volkswagen that did 6l/100km on highway, after replacing the differential pressure sensor with properly working one the fuel consumption dropped to 5l/100km because it was not constantly regening dpf.

On topic of parts cannon cost - there are two 25tonne excavators, same year make model, same work, even when switching operators one machine gets 8-9l/h fuel consumption, other one has 13-14l/h consumption. Machines work 5 days per week 10 hours a day so 1000 liters of diesel is cost of machine running wrong.

New sensors, baking the cans will pay back fast.