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Your van has 4 oxygen sensors. Technically two of them are catalyst monitors. The ones closest to the engine are the oxygen sensors. The one on the front of the vehicle, or LH side of the engine is the number 2 (HO2S21) the back side or RH side of the engine is the number 1 (HO2S11) sensor. The second in line on the front is the catalyst monitor for bank 2 (HO2S22) and the second one in line on the back side is the bank one catalyst monitor (HO2S12). I hope this helps, if so please accept this answer. If you need additional help, just reply back and I will be happy to assist more.
Thanks,
Tim
If it has any kind of code it will fail emmissions testing. It could be an oxygen sensor, or many other things setting a lean or rich code. Vacuum leaks, faulty Maf sensor, plugged fuel filters and other things can all cause lean or rich codes. It may not be the sensors themselves, but something setting the oxygen sensor codes.
Ford Technician
23 years Dealership experience, Ford Senior Master Technician since 2000, ASE Master since 1985