- Oct 12, 2003
- Middleburg, Florida
My "check engine" light came on, and I used Harbor Freight's OBD II code reader to find a code of 420. Looking that up in the Repair Manual, I found out that it involves the O2 sensors. The voltage and frequency modulation is incorrect at sustained speeds between 31-40 mph for 5-10 mins. That's exactly when the light comes on. At this point, I don't know which sensor is bad, front or rear. So, I went to the forum at JT Outfitters and inquired. I was directed to the following website <ghg.net/dharrison> were a diagnostic software package is sold that is OBD II and Windows compatible. I haven't bought it yet, but it is supposed to be a great troubleshooting tool. You can actually see your sensors working in real time. My Cruiser has 118,00 miles on it and I'm opting to just replace both sensors at this time. I will probably buy this software in the future for troubleshooting.