CEL: O2 Sensor Low Voltage

PAKMAN325 · **Joined:** Fri Sep 06, 2013 12:38 pm **Posts:** 35

I've noticed a fuel economy drop in my KK with 117,000 mi over the last couple weeks. Seems I am maxing out at about 20mpg (even with my incredibly conservative driving habits and mostly highway commutes).

Yesterday morning the CEL light came on, but drive quality remained as good as ever, aside from the mileage concern.

Code run at autozone showed it to be an 02 sensor, low voltage. Like an idiot I forgot to get the reference to the bank and sensor number, but I have three questions...

1. I found this sensor replacement on Amazon and I wanted to see if you guys could confirm or verify with probable certainty that this would be an adequate replacement. Amazon says that it fits 2008 liberty's both upstream and downstream, however much credence comes with that. http://www.amazon.com/Bosch-15510-Oxyge ... automotive

2. What are the risks of driving it over the next 2 days until the amazon fulfillment delivers the order? I have about a 30 mile commute as a round trip. Am I just wasting fuel or is there a threat over the next 75 miles or so? Should I try to borrow a vehicle until Friday night?

3. How quickly should I look to replace the other 3 sensors? I know they're only rated to last so long, but I wasn't sure if that's something that should just be replaced as necessary.

tommudd · **Posted:** Wed Oct 09, 2013 1:30 pm

Most will tell you to go to the dealer and not buy Bosch
Some will tell you to replace them all at the same time
I've replaced two of mine so far, one at 120,000 one at 190,000
With it not working correctly you may burn through some extra fuel, all depends
but you do need to know which one it is

PAKMAN325 · **Joined:** Fri Sep 06, 2013 12:38 pm **Posts:** 35

tommudd wrote:

Most will tell you to go to the dealer and not buy Bosch
Some will tell you to replace them all at the same time
I've replaced two of mine so far, one at 120,000 one at 190,000
With it not working correctly you may burn through some extra fuel, all depends
but you do need to know which one it is

So are you a big believer in skipping on Bosch? I've read a few things saying that they're the only reliable 3rd party dealer, and I didn't check on the MOPAR cost. Did you find them pretty easy to locate/swap out?

I went ahead and ordered the one linked, just because I'd like it fixed no later than Friday, so I'll have that ready, even if I end up returning it.

I plan to go back to have the code read and properly recorded... I coach and only had about 15 minutes yesterday to go get it checked out. I made the mistake of not writing down the code number and the sensor/bank.

Leeann · **Joined:** Thu Mar 14, 2013 9:19 pm **Posts:** 523

OEM / NTK (OEM manufacturer) only.

PAKMAN325 · **Joined:** Fri Sep 06, 2013 12:38 pm **Posts:** 35

Wtf... I get into the car to leave work and the light is off. I got 23.6 mpg on the way home compared to 19.4 on the way there.

Why would that be? Temperature? We had a dip over the last two days--below 50-- and this afternoon was 75.

PAKMAN325 · **Joined:** Fri Sep 06, 2013 12:38 pm **Posts:** 35

This morning, the light stayed off. I cancelled my amazon order for the Bosch sensor and bought an NTK one for $3 more. Should I go ahead and replace it even if the light stays off?

tjkj2002 · **Posted:** Thu Oct 10, 2013 10:36 am

A O2 low voltage code can mean many things,more so depending if it's a upstream or downstream O2.Basically it's just telling you that O2's voltage stayed under 100mv for to long and was recorded on 2 trips.Does not mean the O2 is bad as other issues can cause this code.A "lazy" O2 can cause those codes also in cold weather which would require a new O2.

A code is not stating a failed part,just the area to look at.Plus without knowing the code # or which O2 sensor how did you know what O2 sensor to buy? The are placement specific on a KJ,upstream/downstream.

PAKMAN325 · **Joined:** Fri Sep 06, 2013 12:38 pm **Posts:** 35

tjkj2002 wrote:

A O2 low voltage code can mean many things,more so depending if it's a upstream or downstream O2.Basically it's just telling you that O2's voltage stayed under 100mv for to long and was recorded on 2 trips.Does not mean the O2 is bad as other issues can cause this code.A "lazy" O2 can cause those codes also in cold weather which would require a new O2.

A code is not stating a failed part,just the area to look at.Plus without knowing the code # or which O2 sensor how did you know what O2 sensor to buy? The are placement specific on a KJ,upstream/downstream.

I actually misquoted the code. It was a 0135, bank 1 sensor 2, driver downstream, with HIGH voltage.

This is a KK and the part number I initially purchased was the Bosch 15510, but it appears that all four, on the KK at least, are identical. I could be wrong though, as I haven't swapped it out yet.

I don't remember the NTK part number but does it make sense that they could be the same up and downstream? And the lazy or dying o2 sensor could still explain the temp sensitivity too, right?

Scar0 · **Posted:** Thu Oct 10, 2013 11:34 pm

The O2 sensors are the heated type. This code refers to the heating element circuit. It could be an issue within the sensor, wiring, fuse, or ECM.
I found this Video which will show you how to test the heating element within the sensor.
http://www.youtube.com/watch?v=4eBefRoZRFY

tjkj2002 · **Posted:** Fri Oct 11, 2013 7:41 am

PAKMAN325 wrote:

tjkj2002 wrote:

A O2 low voltage code can mean many things,more so depending if it's a upstream or downstream O2.Basically it's just telling you that O2's voltage stayed under 100mv for to long and was recorded on 2 trips.Does not mean the O2 is bad as other issues can cause this code.A "lazy" O2 can cause those codes also in cold weather which would require a new O2.

A code is not stating a failed part,just the area to look at.Plus without knowing the code # or which O2 sensor how did you know what O2 sensor to buy? The are placement specific on a KJ,upstream/downstream.

I actually misquoted the code. It was a 0135, bank 1 sensor 2, driver downstream, with HIGH voltage.

This is a KK and the part number I initially purchased was the Bosch 15510, but it appears that all four, on the KK at least, are identical. I could be wrong though, as I haven't swapped it out yet.

I don't remember the NTK part number but does it make sense that they could be the same up and downstream? And the lazy or dying o2 sensor could still explain the temp sensitivity too, right?

Yeah giving the correct code really helps,change the O2 sensor as the heater has failed just not with a bosch one.

PAKMAN325 · **Joined:** Fri Sep 06, 2013 12:38 pm **Posts:** 35

tjkj2002 wrote:

PAKMAN325 wrote:

tjkj2002 wrote:

A O2 low voltage code can mean many things,more so depending if it's a upstream or downstream O2.Basically it's just telling you that O2's voltage stayed under 100mv for to long and was recorded on 2 trips.Does not mean the O2 is bad as other issues can cause this code.A "lazy" O2 can cause those codes also in cold weather which would require a new O2.

A code is not stating a failed part,just the area to look at.Plus without knowing the code # or which O2 sensor how did you know what O2 sensor to buy? The are placement specific on a KJ,upstream/downstream.

I actually misquoted the code. It was a 0135, bank 1 sensor 2, driver downstream, with HIGH voltage.

This is a KK and the part number I initially purchased was the Bosch 15510, but it appears that all four, on the KK at least, are identical. I could be wrong though, as I haven't swapped it out yet.

I don't remember the NTK part number but does it make sense that they could be the same up and downstream? And the lazy or dying o2 sensor could still explain the temp sensitivity too, right?

Yeah giving the correct code really helps,change the O2 sensor as the heater has failed just not with a bosch one.

Sounds good. I have an NTK part coming saturday. The Bosch order didn't apparently get cancelled in time, so that'll arrive today. I'll have to see if I can return that for cash at a local parts place.

How difficult is it to get the harness unclipped? I read a post on wranglerforum from a guy ranting about how excruciatingly difficult it is. I know there won't be much room to work, but I'm a pretty fit guy, and on paper at least, this looks pretty simple.

huntb · **Posted:** Fri Oct 11, 2013 3:16 pm

PAKMAN325 wrote:

Sounds good. I have an NTK part coming saturday. The Bosch order didn't apparently get cancelled in time, so that'll arrive today. I'll have to see if I can return that for cash at a local parts place.

How difficult is it to get the harness unclipped? I read a post on wranglerforum from a guy ranting about how excruciatingly difficult it is. I know there won't be much room to work, but I'm a pretty fit guy, and on paper at least, this looks pretty simple.

Dunno about the harness, but make sure you disconnect your battery first. I've gotten zapped by those effin things before

Edit: Edited out "censored word"

PAKMAN325 · **Joined:** Fri Sep 06, 2013 12:38 pm **Posts:** 35

Attempted today. Couldn't get the harness OR the sensor out. Failure.

Shot some pb blaster on the sensor. I'll probably try some electrical spray on the harness tomorrow.

Disappointing afternoon.

PAKMAN325 · **Joined:** Fri Sep 06, 2013 12:38 pm **Posts:** 35

Successfully swapped out the sensors today. Took forever and a half, but it's in! Thanks for the help, guys.

PAKMAN325 · **Joined:** Fri Sep 06, 2013 12:38 pm **Posts:** 35

While I was tucking the wiring into place I scoped out the upstream sensors. How in the hell would anyone get to those? And where is the harness?

I'd like to swap out the other 3, but those look much less straight forward, even if everything went perfect.

Greenwing7 · **Posted:** Tue Nov 12, 2013 1:31 pm

I am currently throwing a P2271 code...

2271 JEEP HO2S Signal Stuck Rich Bank 1 Sensor 2
Possible causes
- Faulty Rear Heated Oxygen Sensor Bank 1
- Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
- Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
- Intake air leaks
- Exhaust gas leaks
- Inappropriate fuel pressure
- Faulty fuel injectors
What about the obd code?
The Powertrain Control Module (PCM) detected the HO2S12 sensor has reported a rich condition for an extended period during an intrusive test
Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- High Fuel Consumption
- Excessive Smoke from Exhaust
P2271 JEEP Description
The Powertrain Control Module (PCM) supplies a voltage of about 450 mV between the HO2S high and low signal circuits. The oxygen sensor varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.

The PCM monitors and stores the heated oxygen sensor (HO2S) voltage information. The PCM evaluates the HO2S voltage samples in order to determine the amount of time the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period and determines if majority of the samples are out of the operating range.

This occurred over the last few days when we had a dip into the mid twentys.
any ideas on what to do. I plan on starting with the wiring and moving to replace the sensor. I have noticed that MPG has dropped down to 16/tank and was previously around 20mpg/tank.

Greenwing7 · **Posted:** Wed Nov 13, 2013 10:02 pm

wiggled the wire, CEL now off, guess its position has led to the wires being banged and loose. Will replace when the part comes in.

carlosburitica · **Joined:** Sat Jan 05, 2013 1:07 pm **Posts:** 309

don't know how you guys get those mpg numbers.
not even when my kk was 100% stock i ever got over 16 mph. and that is doing the math.

Greenwing7 · **Posted:** Thu Nov 14, 2013 4:53 pm

It's been below freezing and I've been using the remote start more and have quite a bit of up and down driving in the hills right now.

CEL: O2 Sensor Low Voltage

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