A while back I made some extensive posts about my Bank 2 O2. Posted a graph of O2's from the XcalII datalogger. Bank 2, front sensor was switching slow, and tended to center around.6-.7 volts. Should be .45. Replaced both O2's at 45K miles or so. Datalogged again with new O2's, same problem -slow switching , higher voltage suggesting a slightly rich condition. Swapped Old O2's, same thing. Returned truck to stock program via XcalII, same thing - slow O2, slightly rich.

Sooooo today I'm halfway to work and the SES light is on. A quick trip to Autozone and their code scanner showed code P2198 - Bank 2, front sensor stuck in rich condition. Oye. Cleared the code and restarted the engine and the SES light is off - for now.

So here's the BIG question - why, oh why, would every combination of original and new O2's, custom tunes and stock tunes, make the O2 on the driver's side switch slowly AND show a rich condition, then fail in a stuck rich condition?

I mean, there is two things going on - one is the slow swithcing, the other is the "average" value that the sensor is reading , about .6-.7 volts.

I asked a guy at the dealership about this a while ago and of course he said if it isn't throwing a code, they cant fix it, and, don't worry about it cause the pcm is compensating. When I pushed him a little, he suggested a capacitor in the PCM is not charging sufficiently and therefore the rate of switching is too slow...... huh?

So now it's throwing a code.

Any thoughts on where to troubleshoot would be greatly appreciated.

 

Why is there resistance to checking out a rich condition?
Bad fuel regulator, leaking injectors, air meter, bad leak in the exhaust ahead of the sensors..
The OX sensor only read these conditions and alert to a problem.
The PCM knows they are operating out of limits and tells you.
They are not the problem unto themselves as you have already proven.
Those sensor would most likely work perfect in another truck.

 

thanks for your ideas, Bluegrass. No resistance at all. Just not sure where to start.

No other codes - injectors OK?
Only one side - not the air system? Would affect both sides, yes?
fuel regulator - ??? would that affect only one side? Don't know much about this
Leak in the exhaust-Never noticed anything, don't smell exhaust that close to the front door or engine area, never heard anything that sounded like a leak. Where to look?

I keep thinking something to do with a sloppy or sticking injector allowing a bit more fuel. However, I have been very carefull to use good gas, and good injector/fuel system cleaner. Can I use too much cleaner and somehow cause an excess fuel issue?

Could it possibly be a short/ground in the wiring harness upstream of the O2 connector (behind the block where it is impossible to get to of course). How would I check the voltage on the O2 connector harness? Can I meter that just by turning ignition to start (without running engine) to get the electic system to send voltage to the harness/O2 connector for warm up and signal processing?

 

Waterman,I'm having a difficult time figuring out my cel light.My cel came on about a month ago,i plugged my Diablo in my truck and it came back P0430,catalytic converter below efficent threshold,bank two. I have the high flow cats and an X pipe.I had the cats installed 6 months ago and not a problem.I replaced both o2 sensors,the light went out and came on a couple of days later.I purchased and installed a set of mil eliminators from BBK,removed the neg. battery cable for 20 minutes,installed the cable,4 days later the light came back on and is still on.Everytime i read the code it reads P0430,I am not sure what is going on,I thought the cat is bad,but I cant be sure and before I spend another $120.00 for more cats,I want to be sure thats the problem.I'm taking it to my mechanic tommorrow,hopefully i'll find out whats going on and knock that light out for good.Thanks,good luck.

 

The Ox sensor has a 12 volt heater in addition to the sensor output to the PCM.
You can check for solid 12 volts to the heater pins and for a cross or leakage from the heater supply to the sensor input back to the PCM.
Do not try to measure the sensor 'output' with a resistance meter, only the heater function.
The output can be looked at with a digital for voltage only and should be the same as looking at it with your Scanner while the engine is running.
The heater function can be looked at with just the key on.
With the reading just out of range and slow, I would be looking for possible leakage/cross between 12 volts and the output that may be causing a clamping action of sorts.
Said another way, if 12 volts is leaking onto the sensor leads , the sensor can't change the result very much that the PCM sees; it's .4 volt vs 12 volts.
Test for voltage between the 12 volt circuit and the sensor output preferably with the PCM disconnected so you are not seeing the PCM during the testing.
I know it's a hassle but with times like this you have to go ever deeper until the problem is uncoverd.
The harness that goes out of sight may be able to be moved and affect the results enough to tell if there is a problem out of sight.
Good luck.

 

I imagine you checked the sensor itself for leakage already .

That MIL will stay 3 cycles apart until the problems resolved -- In case you wern't aware of that one already.

 

Bank 1 front, the new Bosch, is almost a flat line. Looks like it is drifting around 0.5 volts. Sometimes it goes up, when under load going down the highway, but just seems to wander around on the SCT display. That is way worse than it was before. At least then it occilated up and down, slowly.

I am afraid I will mess up something with a totally non-functioning O2. Man I wish there was an obvious answer to this.

 

I swapped out the newish Bosch for the old oem O2. Datalogged looked the same, Bank 2 not occilating gooooiinnng uppppp goooinnnggg dowwwn. Tend to stay around .7 or so steadily. When revving, the voltage dropped real low, .1, .2

Loaded the stock tune, just to make sure it wasn't the custom tune (and as I anticipated, it wasn't). Stock tune had same results. In fact, when revving it went to 0 volts!

When I let off the pedal, it sounded like it almost stalled. I can hear it gurgle back through the AF1 intake.

Only this side though. the other bank is fine. Checked hoses and I didn't see any obvious cracks, but there is one large hose off the back of the TB, which had the rubber flaking off, like it was deteriorating. Not cracked though. No sign from what I could see underneath of any cracks in teh exhaust manifold, but the view is limited down there.

Guess I will have to take 'er in to the Great Blue Hope - uhg. These are the same guys that gave me a replacement tie rod end and told me the replacements come with a grease fitting even though the oem is sealed. Uh-huh. Took that back and got the right one. The there was the blend door actuator motor mix up...... pray for me