o2 Sensor Not Responding

[StusRover]

I have replaced all of my O2s with new Bosch sensors. I am having one sensor that was fine, but now when it will go unresponsive after driving for a few minutes. The Downstream passenger side sensor is responsive when I turn the truck on and while its idling in the drive way. It will work for a bit (maybe 5 minutes) once I start driving. Then it goes flatline and doesn't come back on. Eventually I will throw a code for it not responding.

I have ordered another, but seeing as they are $50 a pop, I wanted to see if there is something else I should be looking at for why its works some times and not others?

 

[K-rover]

I had a slow to respond O2 that eventually went dead. After replacing both O2 sensors I was still getting codes. Replaced the connector on the driver side O2 and that fixed the issue. Might be worth a try?

 

[StusRover]

K-Rover - By replace, you spliced in a new clip or did you trace it back further?

 

[K-rover]

I spliced in a new connector about 6" back from the old one.

 

[StusRover]

I swapped in the other new Bosch o2 sensor and again it's unresponsive after a few minutes of driving. The wires go over the transmission. Is that right? I'm thinking the transmission heats up and causes the wire not to respond. Any one have a suggestion?

 

[kcabpilot]

On my truck at least the aft pass side wiring is cable tied to the frame rail to prevent it from fouling on the driveshaft. You're probably going to have to "ring out" the wires while flexing the harness to see if there is a break somewhere. If there is the two most likely points are at the termination on the connector itself or where the cable is tie wrapped to the frame rail.

 

[StusRover]

OK. So I have spliced in a new plug. Which got the O2 responsive again for about 4 minutes. Now it will start fine (when cold) and register .4v. Then about 3 minutes in it will drop to .3, then .1 and then 0. It will remain 0 for the rest of my drive. If I let it sit 30 minutes or so then it usually will respond the same, sometimes needs longer to cool down.

I saw cool down because that is all that I can figure out. Its a heat thing? I have brand new Magnaflow cats and Y pipe. I have tried 4 different o2 sensors. Anyone else have an idea?

 

[squirt]

How repeatable is that 3 minutes?

I'm thinking that you may be reaching the point where the O2 sensor heater should have already warmed the thing up, but it's not doing its job. The timing seems to roughly match what I'd expect.

I assume that you're taking these latest observations in your driveway, so you can rule out wiring that's moving around while driving and intermittently shorting?

I'd look for two things:

1) a consistent failure somewhere in the heater circuit for that sensor - should be easy to diagnose by checking for voltage across this circuit at the connector when running

2) intermittent failure somewhere in the signal circuit for that sensor - triggered by driving around, possibly by wiggling the harness in the driveway, intermittent = PITA for diagnosis

 

[StusRover]

I've tried both and it's consistent in driveway and on the road.

 

[squirt]

OK, so what does the activity on the heater circuit look like?

 

[ezzzzzzz]

Did you use any kind of dielectric grease on the connectors?

 

[StusRover]

I didn't use anything on the connections.

Last night when I finally got a chance to put the multimeter to the plugs to test, I realized that the obd2 was still reading voltage even when the sensor was unplugged. I am going to pull the wires and redo connections. I am guessing that one of them must have come lose? Didn't have time last night to get it to it.

 

[StusRover]

I have reconnected the wires and am getting the same problem. Regardless of the O2 being connected, it will .4 and then slowly drop to 0 and stay. While I had the wires apart, I had to drive the truck to go pick up kids from school one day, so i tucked it up and monitored to see what readings changed, if they did. I got the heater failure code (which is the last wire I hadn't connected yet) as I should have.

I am handy, but not super familiar with electrical troubleshooting. I have an electronic multimeter. Can someone point me to a reliable resource on how to test this and what I should be looking for?

 

[discostew]

OK. So I have spliced in a new plug. Which got the O2 responsive again for about 4 minutes. Now it will start fine (when cold) and register .4v. Then about 3 minutes in it will drop to .3, then .1 and then 0. It will remain 0 for the rest of my drive. If I let it sit 30 minutes or so then it usually will respond the same, sometimes needs longer to coolwa down.

I saw cool down because that is all that I can figure out. Its a heat thing? I have brand new Magnaflow cats and Y pipe. I have tried 4 different o2 sensors. Anyone else have an idea?

I would disconnect one of the sensors when that .4 volt is gone. If the voltage goes back to .4 when it's unplugged then the sensor is probably wet with raw fuel and pulling it low. That half a volt is produced by the ECM to stabilize the signal produced by the sensor, the voltage the sensor makes rides on that same wire. Make sure the red and black wires are grounded when the engine is running.

 

[StusRover]

When you say "one of the sensors" do you mean on that is functioning correctly or the one that is not functioning correctly? Only them rear passenger side is not functioning correctly.

Thanks for the help!

 

[discostew]

The one that's not working

 

[StusRover]

Thanks. I will test shortly.

 

[StusRover]

So I tested as suggested. After it got down to 0 I unplugged the 02 but there was no change. it just stayed 0. Does that help lead us down a path of something else to test?

 

[discostew]

Sounds like its not the sensor.

 

[StusRover]

I got the P1173 code today while driving. Which make sense given the readings, but if its not the sensor what do I need to be looking for?