Oxygen Sensors E430 2000

gang,

my vehicle failed the local emissions testing. My diagnostic output (via Auto Scanner) indicates two errors: 2016 and 2085

2016 - cylinder 1-3 mixture self regulation reach limit (part load) P0170

and

2085 - cylinder 4-6 mixture formulation unit adaptation reaches limit (part load) P0170.

Both point to 0170 (right cylinder mixture adaptation reaches limit value).

The research so far indicates could be several sensors within the fuel system, but hedging toward the oxygen sensor(s). Is this a good assumption?

Also, and if so, are there 2 or 4 sensors on this vehicle? I read there are sensors located in front of,,, and behind,,, the Catalytic Conv. Now, are there two each in front and two each in back of the CC (total of 4)? Or maybe just one each in front and one behind (total of 2)?

I also can not tell which OS should be considered, i.e., they come in 4 types, i.e., sensor with 1-wire, sensor with 2-wire, sensor w-3 wires, and sensor with 4-wires. Yes, sensors do come with connectors, but price is more that 2X to 3X the cost for each sensor when purchased with a connector. Unless you can tell me to get the sensors with connectors, it may be worth the savings to purchase the non-connectorized sensors and reuse existing connections.

If anyone has any input/advise, pls advise.

thanks in advance.

Roger