No 02 voltage to bank two sensor two, dumping fuel out of tailpipe

[OilBurner2003]

Hey guy's, multiple posts today it would seem, I don't wanna spam this forum too much but you guy's have been the most helpful when it comes to my issues.

Here's the thing. Bank two sensor two is stuck at 450.V, all the other o2's move up and down except this one. The wiring to the harness has power, checked it with a test light, I'm not sure about signal. Tried a spare o2 sensor, same thing. It's just completely dead. The strange thing is, It's not throwing a code. Not throwing a code for anything actually. Unplugged the other o2 sensors and never even got a CEL. Same thing for misfires, Runs like hell and no code. During the testing I knew how to do, Fuel is dripping out of exhaust when you go just a little above idle. Obviously this whole thing has been a issue with ignition, but now I'm just confused, so is the mechanic. I don't have high hopes to figure this out obviously until I can find another shop, but if I can do this in my free time I won't complain. Before, I had a p0140, p0157, circuit low voltage for bank one, circuit insufficient activity b1s2. I'm just wondering what that tells me. It's probably because the sensor's were being coated in gasoline...But now only bank 2 sensor 2 is having a no voltage issue. Any advice is appreciated! Someone told me that I should be looking into shorts/bad grounds for the o2 wiring.

 

[east302]

The downstream sensors just monitor catalyst efficiency so a sensor defect itself wouldn’t impact drivability. Now if the converter is clogged then that will show up in the sensor voltages and be another issue that would impact things upstream.

Meaning, this downstream sensor may be a red herring but is worthwhile to get into a working order.

Your fuel trims look pretty good on bank 2, within 10% of each other on long and short term. Couldn’t see the long term on bank 1, though. Are you sure that isn’t just condensate dripping from the exhaust? Pretty normal.

Anyway, I’d think that your downstream sensor should be tossing a DTC P0140 by now. Here’s an excerpt from that code’s table in the 98 manual that would be worthwhile checking the voltage for:




When you checked for voltage, was that using ground through the connector or to the frame? Check it through the connector to verify ground integrity.

 

[OilBurner2003]

The downstream sensors just monitor catalyst efficiency so a sensor defect itself wouldn’t impact drivability. Now if the converter is clogged then that will show up in the sensor voltages and be another issue that would impact things upstream.

Meaning, this downstream sensor may be a red herring but is worthwhile to get into a working order.

Your fuel trims look pretty good on bank 2, within 10% of each other on long and short term. Couldn’t see the long term on bank 1, though. Are you sure that isn’t just condensate dripping from the exhaust? Pretty normal.

Anyway, I’d think that your downstream sensor should be tossing a DTC P0140 by now. Here’s an excerpt from that code’s table in the 98 manual that would be worthwhile checking the voltage for:

View attachment 392929
View attachment 392930

When you checked for voltage, was that using ground through the connector or to the frame? Check it through the connector to verify ground integrity.

I used a test light and put alligator clip on frame, poked D connector with Key on and got a light. You're saying I should poke C For ground and D for power at the same time?

 

[east302]

Yep. It shares the same ground with the other sensor(s?) but there may be an issue in between.

 

[OilBurner2003]

Yep. It shares the same ground with the other sensor(s?) but there may be an issue in between.

Really appreciate you sir, I'll do it and report back.

 

[OilBurner2003]

Yep. It shares the same ground with the other sensor(s?) but there may be an issue in between.

I'll be damned, test light lit right up. I suppose that means both the power factor and the ground is good?

 

[east302]

Yes. Try that first step in that image above - key on, engine off and watch the sensor voltage to see if it drops.

Else, swap it with the other downstream sensor and see if the stagnant voltage moves to that bank with engine warmed up.

 

[OilBurner2003]

Yes. Try that first step in that image above - key on, engine off and watch the sensor voltage to see if it drops.

Else, swap it with the other downstream sensor and see if the stagnant voltage moves to that bank with engine warmed up.

The voltage does not drop with key on engine off

 

[east302]

Per GM, the sensor is the issue. I’d swap with the other downstream one first to see how it behaves.

 

[OilBurner2003]

Per GM, the sensor is the issue. I’d swap with the other downstream one first to see how it behaves.

View attachment 392946

I actually think my app was at fault with the last test. Will make sure it’s working again before I proceed