Volvo's Emission Problem

Volvo Trucks has just admitted to serious engine emission control problems in a new Press Release. The problem is not clearly defined, but rather the press release vaguely refers to it as follows:

The Volvo Group has detected that an emissions control component used in certain markets is degrading more quickly than expected, which could cause the engines to exceed emissions limits for nitrogen oxides (NOx). All products equipped with the component meet emissions limits at delivery; the degradation is due to a materials issue that occurs over time. A full analysis of the issue is not completed and it is not possible to assess the financial impact at this stage; however, the cost could be material.
— Volvo Trucks Press Release

One possible source that fits with this wording is degradation of an SCR catalyst using reductant injection. Another, previous, Volvo Press Release touted the advantages of such as system:

The solution was to improve the selective catalytic reduction (SCR) technology that Volvo Penta had already implemented in its Tier 4i engine generation. With SCR technology, AdBlue™ is injected into the exhaust line and reacts with NOx in the catalytic converter to turn the harmful compound into nitrogen and water. Another crucial part of Volvo Penta’s Tier 4f solution is light exhaust gas recirculation (light EGR). Because NOx is created at very high temperatures, the EGR further contributes to reducing NOx by lowering the peak combustion temperature.

How it’s different
Many of Volvo Penta’s competitors have attacked the problem from another angle, configuring their base engines’ combustion rate to produce low levels of NOx but emit high levels of PM. Their solution is to add a diesel particulate filter (DPF), which captures the soot and periodically incinerates it down to harmless ash in a process called regeneration. Though effective, this approach has its own drawbacks, including higher fuel consumption. Furthermore, a DPF requires costly maintenance and must be replaced regularly. Overall, a DPF system requires many extra parts — from air pumps and compressors to ignition coils — all of which can fail or need replacing.
While most engine manufacturers installed a DPF to meet Tier 4i and SCR to meet Tier 4f regulations, Volvo Penta uses just SCR in its Tier 4F engines — a simpler, more straightforward solution for customers, with fewer parts and less maintenance than a DPF.
“Because we believed that reducing NOx and PM emissions to Tier 4f levels could be achieved with just SCR, we put all our effort into improving that technology — and making sure we didn’t need to use a DPF, which can end up being more hassle for customers,” says David Hanngren, manager of industrial product planning at Volvo Penta. “It would have been far easier for us to use a DPF, which was already an existing technology. And ultimately our competitors’ engines with DPFs emit the same low levels of PM and NOx as ours do. But because they’re configured to perform at optimum levels, burn less fuel and produce very little smoke, our Tier 4f engines have ended up being a much better solution.”
Though Tier 4 Final is major step forward, the process of lowering emissions in off-road engines isn’t over yet — there are more stringent regulations in the pipeline for years to come. Volvo Penta is already working with innovative technologies to meet future regulations — while continuing to keep customer needs at the forefront of every new advancement it makes in emissions reduction.
— Volve Trucks Press Release

So we looked to see if Volvo has any patents describing such as system and found US 9,097,159, related to a method for detecting urea deposits in an exhaust line of an automotive vehicle, a method for eliminating urea deposits and an automotive vehicle adapted to such methods. The abstract explains the method is for detecting urea deposits in an exhaust line of an automotive vehicle and includes determination if an exhaust gas's temperature is reached, if the result of determination is positive, stoppage of urea injection, and determination of the quantity of NOx in the exhaust gases on the outlet of the selective catalytic reduction system. A comparison is performed between the quantity of NOx determined on the outlet of the selective catalytic reduction system and a theoretical quantity or a measured quantity of NOx produced by the internal combustion engine. If the comparison shows that the quantities are different, it is considered that urea deposits are present in the exhaust line.

Volvo may have discovered their in-use problem via a diagnostic approach just like the one above. The question now is - what can they do to solve the issue. No doubt, whatever the solution, it may generate important IP that other competitors may not even realize they need.