Source: European Parliament
The type-approval emissions legislation for heavy-duty vehicles[1] (Euro VI) sets out that emission control monitoring systems shall be operational at ambient temperatures between -7 °C and 35 °C. The vehicle manufacturer may use a heated reagent tank and dosing system to ensure compliance to the pollutant emission limits. A driver warning system informs the driver when a low reagent level, incorrect reagent quality, too low a rate of reagent consumption, or a malfunction, has been detected. This should lead to operation of a driver inducement system if not rectified in a timely manner.
Recognising potential problems of using reagents in extremely cold temperatures, the Euro VI Regulation allows vehicle manufacturers to apply for a derogation, disabling system monitors at ambient temperatures below -7 °C in the case of frozen reagent. System monitoring may also be temporarily disabled at other ambient temperature conditions upon determining that the manufacturer has demonstrated with data and/or an engineering evaluation that misdiagnosis would occur at those ambient conditions because of its effect on the component itself (e.g. component freezing). Such derogation requests would need to be discussed between the manufacturer and the Type Approval Authority of the Member State that handles the emission type-approval application.
- [1] Regulation (EC) No 595/2009 of the European Parliament and of the Council of 18 June 2009 on type-approval of motor vehicles and engines with respect to emissions from heavy duty vehicles (Euro VI).