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P0135 - O2 sensor getting tired *** It's a fix ***

posted Apr 20, 2016 15:09:51 by alandk
When driving got code P0135 and check engine light came on, the best explanation I found was this:

"The heated circuit in the oxygen sensor decreases time needed to enter closed loop.
As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The ECM tracks how long it takes for the oxygen sensor to begin switching. If the ECM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0135."

I measured the heater resistant to be 9 ohms on the two white cables.
With motor running there was 12V on one cable and 0.3V on the other,
so the heater circuit is working OK, then checked for bad connections,
but none was found. Cleared the code with scanntool.
Next day the P0135 came back, but not when starting engine, but under driving.

I then took some snapshots of the scantool, and it shows that the O2 sensor (B1S1)
is getting tired of sending signal when it warms up.
It will stay around 0.5V and STFT shows 0V, this must be Open Loop mode.

I did it again the next day and again the O2 sensor is fluctuating at start,
but again gets tired.
The O2 B1S2 after the cat shows rich when the error occurs.

The O2 sensor has run 60K km, and needs to be replaced.




[Last edited Apr 29, 2016 11:34:17]
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12 replies
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alandk said Apr 20, 2016 15:14:36
Dang, not all of the pictures are shown on the forum,
you have to click on the pic. to see the timeline in seconds.
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Dylan said Apr 20, 2016 16:33:30
I then took some snapshots of the scantool, and it shows that the O2 sensor (B1S1)
is getting tired of sending signal when it warms up.
It will stay around 0.5V and STFT shows 0V, this must be Open Loop mode.


As you probably know we need the O2 to be at operating temperature for it to be functional. Make a custom list with scantool if posssible. Are you able to see the data PID for open/closed loop?
Did you perform any other tests concerning the O2?
Belgium, Europe
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Dylan said Apr 20, 2016 17:18:54
Checked the P0135 and it is indeed a heater circuit fault code for the upstream O2 of bank 1.
Belgium, Europe
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Tyler said Apr 20, 2016 17:40:16
I suspect you're working on a GM, but what's the year/make/model on this one?

It does seem like the B1S1 O2 is struggling to warm up, especially in that last capture. I kinda like the old time-to-activity O2 monitors, relying on sensor activity and not heater circuit.

I've got some very similar captures from a late 90's GM truck with heater codes, same monitor design. Very easy to pick out failing sensors once you're familiar.
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alandk said Apr 21, 2016 08:08:18
From this morning, 10 deg. Celcius.
Timeline set to 300 sec.
After 80 sec, the upstream O2 sensor gets tired and no more STFT signal.
At 170 sec. heavy acceleration.
At 200 sec. deacceleration.
It's a Renault 2012.

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Inge_Jeppesen said Apr 21, 2016 19:05:55
Any loss of engine oil or coolant. I am thinking polution of the upstream o2. 60K was a bit to early to fail?
Norway
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AndyMacFadyen said Apr 21, 2016 20:21:12
I would really want to check what happens to the b1s1 heater current when the engine gets warm.
"Rust never sleeps"
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alandk said Apr 25, 2016 16:32:16
Just tested the heater circuit with an oscilliscope.
With ignition on, there is +12V on both wires.
When engine is started, the PCM side drops to 0V for around 30 sec.
Then the scope shows two 10mSec wide pulses, 50mSec apart, every 200mSec.
For 5 sec. the amplitude is +12V, the next 5 sec. the amplitude is +2.5V,
this is repeated all time.
When this test was done, the O2 was around 350mVolt, and STFT was at 0V.
When the engine is stopped, the voltage stays at +2.5V for a minute,
then a relay clicks and it drops to 0V.

@Inge_Jeppesen, maybe you are on the right track,
the engine was lacking compression on two cylinders, and used oil.
The engine was replaced at 50K km with a new one, so the O2 sensor
should maybe also have been replaced.
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alandk said Apr 29, 2016 11:33:42
pic1.
The code was cleared and the O2 sensor was replaced with the ½ tool.

pic2.
Old and new.

pic3.
The first start up, voltage rises after 10 sec., the old one was 30-50 sec. Just idle.

pic4.
At 40 sec. the RPM is increased to 1500 RPM.
At 100 sec. the RPM is increased to 2500 RPM.
At 170 sec. down to idle, and LTFT goes from 0% to -3,9%.
At 240 sec. WOT and back to idle.

At 130 sec. the O2 DOWNSTREAM (edited from upstream) goes rich almost until the WOT at 240 sec.,
is this part of the learning for the LTFT....

Click on the pic. to see all





[Last edited Apr 29, 2016 17:57:55]
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Dylan said Apr 29, 2016 17:34:56
At 130 sec. the O2 upstream goes rich almost until the WOT at 240 sec.,


You mean red trace? Bank 1 sensor 2 ??
Belgium, Europe
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alandk said Apr 29, 2016 17:56:39
Yes, the red trace is downstream B1S2 , not upstream...
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Noah said Apr 29, 2016 18:05:51
Nice wrench!
Massachusetts, USA
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