LiteOn 851 does not produce PI or PO errors.
It produces variable burn quality on various different media. The quality is determined by lower level disc/burn characteristics like pit jitter, asymmetry, etc. These are not measurable using home grade dvd burners.
This results in PIE, PIF, POE and/or POF errors in the reading process.
LDW-851 as a reader does usually produce more errors in reading than some later 16x LiteOn models (like SOHW-1653s). As such, it is a useful scanner (IMHO) as it does not give you an overly optimistic view of the burn quality (like most 16x LiteOns often do), but as a burner it is quite far from the current best.