FlamingoGT

I'm looking at replacing some of my O2 sensors, and am looking at probably Denso, NTK, or Bosch.
Are one of these better than the others, or conversely, worse than the others? Or is there another brand in this same price point I should be considering?
I have been getting heater related codes and am going to do some more troubleshooting this weekend, but these are the original sensors so I am thinking I may be just as well of replacing them anyway. Are there any physical differences between the front and the rear sensors (I know about functional, just asking about physical)... some places I look have different part numbers, others use the same part number? For all intents, it is a stock exhaust system.

Thanks.

cliffyk

There are different "pigtail" lengths, the two front sensors being the same, with the two rear sensors each being an odd-ball--that's why the different part numbers.

Some will throw up cautions about Bosch sensors, mostly because that's what the FLAPS sell (and as we all know the chain parts stores sell nothing but low-quality junk) however I have never had a problem with them. The front sensors on my '03 are Bosch, with 45k miles on them and still running fine. Nearly all wideband O2 systems use the Bosch LSU4 sensor.

Functionally all narrowband Platinum-Zirconia O2 sensors are identical. They are all constructed nearly the same (via the Nernst principle)) and all produce the same output voltages a that is a function of the chemistry, nothing else--read more here if you like.

What were the codes you pulled, there's no point in replacing a good sensor. The heater circuit should measure 3.3Ω give or take a bit--if much less it's shorted, if infinite then it is of course open. The sensor can be bench tested with a propane torch--there's a link to the procedure for doing so at the top of the page linked above.

FlamingoGT

0141 and 0161.
I checked the connectors closest to the sensors (the ones on the transmission/bell housing) and they seemed good, but I didn't do a ohm or volt check yet (that was planned for tomorrow too). I couldn't follow the wires much further than that to see if there were other connectors to check.

FlamingoGT

They are reading at about 7Ω... is that close enough to 3.3Ω for these? I can't get the sensors out right now to do any further testing on them (need to find a breaker bar or similar).
It also appears that all of the pigtails are the same length, the only difference I noted while under the car is that the front sensor's wires have a green(ish) sleeve while the rear 2 have a gray (or dirty white?) sleeve. To the best of my knowledge, these are the original sensors (I got the car with about 28K miles on it, and I have never replaced them),

cliffyk

The stock sensors should have the following wire colours:

Front driver's: red/yellow and red/white for the heater; red/black for signal+, gray/red for signal- (gnd);

Front passenger's: red/yellow and yellow/light blue for the heater; gray/light blue for signal+, gray/red for signal- (gnd);

Rear driver's: red/yellow and tan/yellow for the heater; violet/light green for signal+, gray/red for signal- (gnd);

Rear passenger's: red/yellow and white/black for the heater; red/light green for signal+, gray/red for signal- (gnd);

If the colours are not those then they are not stock sensors, also the heater resistance of 7Ω is all wrong--this is from the 2004 shop manual:

uberstang1

I run bosch sensors from FLAPs with zero issues as well.

cliffyk

Those are rear sensor heater codes caused by it drawing too much or too little current--judging by the 7Ω reading you made, and these codes, the rear sensors are either defective, one of the 6Ω universal replacements, or just the wrong part...

FlamingoGT

Considering they worked fine for 6 1/2 years, I am going to go with defective.

As these are both the rears, would a MIL eliminator work for this problem, or am I just as well off replacing the sensors?

cliffyk

Well, at 7Ω heater resistance they are bad/incorrect (this was with the sensor disconnected from the harness, right?)

MIL eliminators work by filtering the signal from fully functional and installed rear O2 sensors. Even if they did work with bad sensors they would do nothing to correct the PCM's monitoring of the heater circuits--read more about MIL eliminators here...

The rear sensor's, including the heater monitoring, can be turned off in the turn; however this will also cause an immediate emissions test fail in states that first check PID 0101 as the catalytic monitor test will show as unavailable. Cat monitoring is required by Federal law, and if switched off it's a fail in states that test for it.