General Motors' European arm, Opel, is recalling 47,000 of its Astra cars because of a faulty oil- pressure sensor, the company said in Ruesselsheim, Germany, on Monday, according to dpa. Opel said the cylinder-head sensor was at risk of ageing and becoming porous, allowing oil to escape. If this happened, engines would smell strongly of oil and smoke would be given off. Astra models G and H from the period 2003-05 with 1.6-litre engines were affected. Opel is to write to the owners, advising that garages will exchange the sensor without charge.