Let’s talk about exhaust aftertreatment demons. They scream at you in the form of warning lights on the dash or, worse, a repair bill you weren’t expecting well into the four figures and, sometimes, five figures. Other times that bill is spent on nothing more than diagnostics as days turn into weeks with recurring issues mechanics are routinely stumped by.
Hope for an affordable solution fades with each recurrence – dash lights in the form of the upside-down triangle, a laptop screen filled with codes that are difficult to understand. The lost days, the stress of truck payments, growing credit card bills … all of it is enough to make an owner-operator doubt his or her choices. It wasn’t supposed to be like this, right? You purchased a newer used truck – still under warranty, the safety net you needed while traversing the high-wire risk of ownership. Right?
Meet John Osinga of Lynchburg, Virginia, a successful and financially stable trucking business owner since 1980. In 2019, John did just that, investing in a 2015 model with 377,000 miles on the odometer and a brand-new diesel particulate filter. This was to be an upgrade from his 2003 Kenworth T2000 after 1,700,000 miles.
Newer truck, he hoped, fewer issues.
The trouble started in the second half of 2020 as the rig approached 500,000 miles. First with the dash warnings. Then, when he took the rig in for maintenance, various sensor replacements.
He got to something of a “final straw” point as he was exiting a customer’s facility and, at the guard shack, the de-rate warning lit up, meaning at best John could drive a short distance at 5 mph before everything shut down entirely. John returned the loaded trailer to the yard, called to arrange for a repower, and had the truck towed to the last shop that had worked on the aftertreatment system.
They once again performed a computer diagnostic check, and what was really needed was a video scope of the internal parts to look for the cause. At last, they discovered more than one issue. John had the DPF cleaned and replaced, and it didn’t appear the be in the proper position (something some mechanics note can happen when excess back-pressure builds up). Additionally, they discovered that a diffuser plate that the diesel exhaust fluid doser sprays against was broken and had fallen out of place, causing the DEF not to atomize into the fine particles needed to work properly. The cause was unknown. Osinga and I speculate it could have been corrosion from the DEF itself.
