Can the s300 do digital input for the wideband signal? If it can, much better going down that route than using 0-5v analog. Thought its not very common, ive seen solid levels of EMI in some cars that send things out of whack (imagine like +-0.1v of noise... if the controller output is linear between 0.5-4.5v your looking at 5% inaccuracy simply due to EMI).

If you do go down the analog route and the s300 has some flexibility, try to avoid setting 0v/5v as any reading. Rather set it up so that if it hits either of those two so the CEL comes on. if it ever hits 0v/5v you know somethings gone wrong with either the sensor or wiring (nothing to do with the wideband really, but rather any analog sensor system.. try to avoid using power source voltage or ground as a valid measurement)