A quick summary: The DPF indicator lamp in our 2020 New Aire (with only 3000 miles on the odometer) had come on twice within 90 miles, indicating a parked regen was needed immediately. The first time we pulled over too late (5 miles after the indicator began blinking) and were rewarded with a $1500 mobile service bill. The second time we pulled over in the middle of the road and performed the regen ourselves. We made an appointment at the closest Cummins dealer (230 miles away) and attempted to drive there.

Why did we make the decision to drive (and risk another DPF shutdown) vs. the determinism of having our RV towed to the dealer? Because that 230 mile drive was very different from our prior drives that potentially exacerbated the problem. It did not require pulling steep grades (9%) at low speeds (15 mph), which greatly increases the rate of particulate accumulation on the diesel particulate filter. Rather, we would be mainly descending out of the mountains at speeds around 55 mph. Our gamble paid off: We made it!

We went to the Transwest Fountain Freightliner service center

Once at the dealer (Transwest) in Fountain, CO it took a few hours after our appointment time for the mechanic to look into our problem, but then he quickly found something amiss, that is his own words, “I don’t know if this is the problem, but I do know it ain’t good”. He found a large piece of paper (6” x 6”) inside the engine air filter. That piece of paper has Newmar markings on it, with our date of manufacture and serial number on it. Seems like a bad place to store a piece of paper. The mechanic pointed out the paper would dramatically decrease airflow, making the engine work harder and therefore produce more soot, making the DPF need more frequent regens.

The paper was in our air filter, the large silver cylinder on left

The paper found inside of our air filter

Could that additional soot have caused our DPF shutdown problem? No one knows, but it’s a reasonable theory. Given we didn’t put the paper in the air filter, Freightliner is paying for the service to diagnose and remove it (they also put in a new engine air filter for good measure). Now we attempt to get Freightliner (or Newmar) to pay our $1500 mobile service fee since we now have proof it wasn’t our fault the stop engine light came on.