Splicing into the old harness is possible, but can yield poor results. Bosch sells a universal one with a splice kit that crimps the wires correctly and couples the insulation so that theoutside air can be accessable to reference the sensor as it is in the OEM manufactured wiring harnes. If you don't do it correctly the sensor will give bad readings. This has worked for some, but if you want it to work correctly for a long time, buy the OEM sensor. I personally see splicing too much of an effort for little cost savings and potential premature failure/ incorrect performance of the sensor.