Poolman, excuse me for not coming back sooner. Checked my mileage again, and it is still not back to what it used to be. So I definitely have a problem. Following your advice I went to ask for price on an oxygen sensor at car parts shop. My sensor, reading the text in flashlight illumination with sensor in place (this is my daily driver) says

BOSCH
020

when I try to read the lettering while sensor still in place. The parts store offer me a "universal sensor", which is from FuelParts (www.fpuk.co.uk) and similar with my sensor has two white leads and one black. My two white leads go to one connector (same type as injectors connector) and the black lead goes to a second somewhat smaller connector just at top of firewall below rear hood end. The sensor from fpuk reads:

BOSCH 086 09 60 982
0258 003 913
on the sensor itself. The numbers on the box from fpuk are :

86300
3 wire Zirconium
EM-LB-A-4
then a barcode which has the number:
029406 000198

I am curious to know whether I should buy this sensor, or should opt for something more original. The instruction from fpuk says the sensor leads should be shortened by 50 mm. Is that really inmportant? leads are leads aren´t they, they should not offer any extra resistance??? Is polarity of the two white leads an issue? If so, how do I determine it?

Many thanks in advance,

Gustafkalle