Downstream O2 sensor issue

[Peter Kovacs]

Hi

First of all I have to say that this site has been a great help for me in the last 1 year and Eric, you are 1 of the best that I have ever come into contact in regarding automotive field. However, I have not found too much of a help that I need with my recent issue. It can be me but I just cant find any help, hence I am opening a new topic. Please help.

I own a Vauxhall Corsa 2002 1.2 SXI with a Z12XE engine. Now this car has gone through many services in the past. Strating from water pump replecament to O2 sensors and many many things between I dont think it is necessary to mention. Long story short. At this moment I have engine codes p0136 and p0141 in the same time. I know it is refers to low voltage and heater malfunctions on downstream o2 sensor. My issue is, that it has been changed twice now but the problem still occurs. OBD scanner showing 0.5 volt constantly. No leaks in exhaust since I have changed that one as well and double checked it before installing. And I have also checked the fuses, no blown fuses and checked if there is 12 V going from the battery to the connector for the o2 sensor. What is strange that there were some voltage in the earth cable as well. Cant remember how much but sure there was some. Now I think it is not normal, but I am not a proffessional thats why I write in this forum. Please help me out where to look next, also I cant find any wiring diagram for my paeticular car.
Again, any help much appriciated.
Thank you.

Peter

Topic

[Ole Eggers]

If the heater is malfunctioning and the O2 sensor has been replaced, I’ld look for problems in the wiring. Lets say there is a short from the heater circuit (12V) to the O2 sensor circuit (which generates between 0.1 and 0.9 V ) you might get the problems you are experiencing. Find a wiring diagram and start measuring 🙂

[Peter Kovacs]

Yeah, thats what i wanted to do, but could not find any diagram. Any ideas where can I find it? Also, what I am worrying about is the other code which shows low voltage. Is it the same issue? Or is it something to do withe the catalyst?

[Ole Eggers]

A Haynes Manual would come in handy, wouldn’t it ?
I have one for the facelift 2003-2006. I assume it’s the same wiring ?
Is your tester / OBD scanner capable of showing live data ? The downstream O2 sensor should be fairly steady around .5 volts during operation. Upstream should vary between .2 and .8V at around 2-3 Hertz.

[Peter Kovacs]

I do have the manual, but it does not include the wiring for the o2 sensor and its circuits. Yeah i do have and the live data show .5 v at all time.

[Ole Eggers]

I can see you are right about the Haynes missing wiring diagram for the engine. I do however, have access to TIS2000 from Opel and I’ve added a PDF for you. I hope this helps. You want to be looking at B57 which should be your secondary O2 sensor. B166 is the primary. I hope this helps.

Attachments:

• WiringZ12XE.pdf

[Mike]

There is one more possibility:
It seems that, unlike most vehicles, the Vauxhall Corsa oxygen sensor plug can actually be plugged in the wrong way and ruin the sensor.

“Had one on a Corsa the other day where a garage had replaced the sensor but still had a lambda fault so they asked me to have a look, realised straight away it was plugged in wrong, the 12v heater supply voltage destroyed the sensor at Ignition On so i advised them to replace the sensor again and plug it in the correct way around this time, they were rather embarrassed to say the least.
The problem is the locking tab on the plug will go over the locating peg thats on the loom plug so in essence the plug can go on both ways, easy done on the back of the engine where its dark. ”

Long thread found here:
http://www.vauxhallownersnetwork.co.uk/index.php?threads/lambda-oxygen-sensor-fault-please-help.466640/page-7

It may or may not be the issue but it’s certainly worth investigating.
As you see, the sensor gets destroyed, so you would need a new one.

[Peter Kovacs]

That is something that I am sure that it not happened. Have checked it several time, to make sure they connect it correctly and when they did it it was on a ramp so there was no issue with visibility. The only thing that I can think of is there is a short in the cable somewhere. In the next week I am going to take it apart and have a good look on the wiring. Will update you if I found the issue. In the meantime if there is something else you guys can think of, please let me know.
BTW thanks for all the help, have a nice weekend

[Author]

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