The Energy Saving Trust, which runs CVRAS with the Low Carbon Vehicle Partnership, withdrew the accreditation after problems were identified between reported and actual test results.
“In total, 16 retrofitted buses belonging to three separate companies have so far been identified as having been affected,” said Matthew Eastwood, head of transport at the Energy Saving Trust.
He added that the organisation is “working to identify any other vehicles and companies that may have been affected, and we will work closely with those affected to resolve the issue”.
Nigel Standley, managing director of GreenUrban, told Transport Engineer: “We acknowledge there has been an internal issue that has caused the disparity, but we assure fleet operators that the ecoNOxt system is fully capable of meeting required performance – not only in the test laboratory, but in real-world service.
“We are endeavouring to work closely with EST to resolve the situation, and have a full test and development programme planned subject to test laboratory availability from now through the whole of 2019.”
CVRAS is a certification scheme for manufacturers of retrofit emissions reduction technology to enable operators of legacy fleet vehicles to comply with clean air zone requirements.
For more details on CVRAS, including a list of approved companies, click the link below.