97 Ranger, 4x4, 4.0L. It runs very rich, ton's of black smoke. Ran codes and got:

P0141-O2 Sensor heater ckt. malfuncton bank 1 sensor 2
P0135-O2 sensor heater ckt malfunction bank 1 sensor 1
P0155-O2 sensor heater ckt malfunction bank 2 sensor 1
P1132-H02S fault
P1152-H02S fault

No other codes. I purged memory and drove it around, checked again and the same codes showed up.

Checked the HEGO power fuse and it's ok. Unplugged the left cyl bank hego and the one after the cat. Could not reach the $#%@& one on the passenger side. Checked the heater ckt. on the HEGO's and got the correct resistance. Turned on the key and checked for voltage at the harness. The one behind the cat checked ok. The one on the drivers side read battery voltage on both heater pins. I don't think there should be voltage on both sides of the heater though. Plugged them back in and checked for continuity and voltage at the PCM and thats ok. I checked the voltage at the ECT and they are within acceptable range.

I don't think three cat's will go wrong at a time especially since the heaters seem to be good. The voltage on the harness HEGO plug at the drivers side bank is curious.

Anyone have any ideas?

Thanks

btt

I have the same problem (and same codes) with my F150, however i tracked it back to a cracked exhaust manifold :) i'd make sure you have no exhaust leaks first. I got looking at it, and noticed that the whole back half of the manifold cracked wide open, and it's finally started to spread around the whole mainifold. only difference is that mine is a 2k f150 V6

-Jeff