UPDATE 1-VW to close main plant 1-2 days a week due to new emissions tests

* VW says WLTP emissions issues cause factory delays - memo

* Wolfsburg and Zwickau plants face shut downs - memo

* New WLTP test procedure delaying road certification (Adds context on WLTP, Audi)

HAMBURG/FRANKFURT, June 26 (Reuters) - Volkswagen plans to shut its main Wolfsburg factory for 1-2 days a week between August and the end of September to deal with problems caused by new engine emissions tests, the German carmaker told employees on Tuesday.

Volkswagen (VW) is the second large carmaker after Daimler to acknowledge a potential dip in sales triggered by stricter anti-pollution test procedures.

A new Worldwide Harmonised Light Vehicle Test Procedure, (WLTP), based on real-driving data rather than theoretical scenarios, has resulted in higher carbon dioxide emissions readings for certain vehicles, delaying official road certification and sales.

Due to the delays, VW is throttling back production of some models at various plants, following in the footsteps of Daimler which last week blamed WLTP and a trade spat for lowering its profit guidance.

VW will also close its Zwickau factory on some days and components manufacturing will face resulting delays, the company said in a statement on its internal website.

The group's plant in Emden will be closed too on some days in the third and fourth quarter due to lacklustre demand for mid-sized cars, the memo said. VW builds its Passat model in Emden.

VW's premium brand Audi on Tuesday said Germany's KBA motor vehicle authority would pay a visit the company's Ingolstadt headquarters on Wednesday to receive a briefing about progress in dealing with emissions issues. (Reporting by Jan Schwartz and Edward Taylor; Editing by Mark Potter)

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