purchased this one, as others on here have bought it. http://cgi.ebay.co.uk/Diagnostic-Sca...item45f2cd9c7a

Now i have an error on startup with the spanner light that goes out after a few mins, but this reader dosn't detect any codes, but will allow me to reset the light, my grandads dawoo matiz also has an error but again reader shows no codes and wont reset light, my wifes astyra 1.7 cdti has been sitting a few days and when she drove off out this afternoon, the spanner light came on along with what i think is the battery light, plugged in reader and no codes found ? and wont reset the codes, is this normal or do i have a faulty code reader.