A senior Volkswagen engineer has exposed why technical differences between European and US-spec VWs have ensured that one software fix can’t be applied to all emissions-cheating cars.
Speaking in yesterday’s Transport Committee meeting, Oliver Schmidt confirmed that physical differences between the exhaust systems of European and US VWs meant that each region needed its own bespoke recall plan.
He explained that Euro 5-spec diesel VWs in the US feature a more comprehensive filtration system compared with equivalent cars in the EU.
“In Europe, there is no NOx after treatment on the system, you only have an oxidation catalytic filter and a particulate filter,” he said. “So there is nothing that reduces the nitrogen oxide on the Euro 5 engine.
“On a US engine, on older generations you have a lean NOx trap, and on the newer generations you have an SCR selective catalytic reduction system. In the US, the [ECU] software influenced the function of those two systems, but they are not present [in European cars].”
Cars from each region will need their own fix, but VW UK boss Paul Willis confirmed that it wasn’t simply a case of one fix for each side of the Atlantic either.
“In Europe, for 1.2 and 2.0-litre diesels we have a software fix – the fix starts on week nine [of this year]. But for the 1.6-litre diesel engine, there’s a software and hardware change that’ll commence from month nine.”
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Schmidt went on to explain that the EA189 1.6-litre diesel engine, which is fitted to 430,000 UK vehicles, will need its flow transformer (which measures the volume of air flow into the engine) changed in order for the software fix to work.
“In the configuration that was brought to production, the onboard computer couldn’t get a proper reading of what was going on, so the actual volume of air was not what we read on the sensor,” he said. “Our new transformer – or flow rectifier as it’s sometimes called – gives you a laminar [smoother] air flow that can be more easily measured.”
This change allows the ECU to accurately inject the correct amount of fuel into the engine, which VW says will improve efficiency.
Schmidt compared the software and hardware fixes with upgrades to smartphones: “What we do on the 1.2 and 2.0-litre is we put new apps on your phone, so we are only changing calibration data. But on the 1.6, we give you a new operating system.”
Willis said VW was confident its fixes would be enough to bring affected diesel engines into line with the law. He added that VW was going beyond its legal requirements to ensure its diesel emissions were reduced.
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“Though the NOx trap we have been using is sufficient to pass emissions tests [with the software fix], we are still going to fit all EU diesels with our SCR system between 2017 and 2020,” he said. “We are also developing all future diesels to work towards SCR systems.”
