so... 2003 gc overland w/ the big v-8 low miles. has two codes 0051 and 161 . both are " bank 2 " o2 sensor related ... one heater and the other heater circuit. ive ordered up a workshop manual so i can understand whats what but until it gets here a few basic questions , please..

1) there appear to be 4 - o2 sensors on the car bank 1 and 2 and front and rear... which bank is bank 1 and are these sensors difficult to access ? special tools ? anything magic required ?

2) the code makes reference to the " o2 heater circuit " ... is that just a catch all phrase or are there relays and control units that drive these sensors that i need to look at or will changing out a bad sensor fix the " circuit " as well ?

3) generic sensors ... clearly about a dozen people make what they claim are compatible sensors from the cheapest chinese to bosch ones. are there any generics that are better than others and are there any that don't require cutting and splicing the plug as some that ive done require ?

4) does anyone have any experience removing the cats on these motors in the interest of freeing up the exhaust a bit and making the milage a little better ?

thx

 

Near as I can tell Bank 1 is driver's side (#1 cylinder side) and all 4 sensors are the same. On 2001 and later there is a relay that supplies voltage to them. Earlier models used either the fuel pump relay or the ASD relay to supply voltage. The signal output is in the range of 100 to 900 millivolts so the condition of the wiring is important. They say not to cut and splice the wires.

It is against Federal regulations to remove the cats and no state will pass a vehicle without one, except maybe Florida who doesn't inspect vehicles at all. The best you can legally do is use a high-flow muffler and larger pipes.

 

understood. no laws at all here in the carribean but general consensus from research is that it does more harm than good anyway. since the other three sensors are apparently good, my presumption would be that whatever is supplying the power is ok so it seems the sensor is the easiest answer. any idea which ones are any better than others ?

 

I used Bosch on my '97 with good luck. It had the plug on it already.

 

if the emissions label under the hood referrs to "California Certified" then you much buy those o2 sensors from the dealer. The o2 sensors "rated" for the replacement on the outside market do not meet the criteria for the PCM programmed for California.

 

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i wasn't aware of that but ( without looking ) im certain this isn't a california car. it was either long island or miami. having said that, i am curious... is that specification reffering to a DIFFERENCE between ca certified and all others or just a relative quality/spec ? that is to say, does jeep have 2 dif part numbers ? ... one for ca and one for everywhere else ?

 

Yes, California emission regulations are much more intense that Federal standards.