I have a 1997 VW Jetta and the check engine light is on. I failed the emissions test and the code read that i have an O2 sensor with no activity. I replaced the faulty sensor, but failed emissions again. The code this time read no circuit activity. There was a faulty wire in the circuit, I replaced it and the check engine light turned off. I went to get it tested again, and I failed. The check engine light "forced itself on" (as it said in the report) and the code came up as "no circuit activity" and "system to rich." I have an OBD and I cleared all of the codes before my test, turning the light off, but the light "forced itself on" again causing me to fail. Does anyone have any suggestions?