O2 heater circuit problems (?)

Arildoss

New Member
Hi all

Its been a while, but that is because my belowed A2 has worked perfectly until some weeks ago.
In short, i am getting codes for the rear lambda probe heating circuit

17513 - Bank 1, probe 2 heating current circuit short to positive
17526 - Bank 1, probe 2 heating current circuit open circuit

Some weeks ago the alternator rectifier went bad causig strange things to happend.
I changed the alternator but the MIL will not go away.

I also getting codes for the rear door locks and i have studied the workshop manual current flow diagram and i have found that they share the same earth connection (249, Earth connection -2-, in interior wiring harness) as the fuel pump relay but i can't find that connection, could anyone please tell me where it is? The fuel pump relay powers the O2 sensor heater circuits.
I must add that the rear door locks are working, i can't see anything wrong about them

I dont have VCDS but a cheaper iCarSoft CR Pro.
When i connect the scanner and looking at the O2 sensors live data they acting very differently, the front sensor are laying steady at 80 ohms and it stays ON always. The rear sensor resistance are fluctuating at 100 - 300 kohms and are turned ON and OFF alternating witch is correct according to the workshop manual

The scanner always pointing to the rear sensor but as long as they share the same power supply i would think both sensors would behave strangley if there was a problem with the power supply. Both sensors are new and i have changed the fuel pump relay and the ECU but no luck yet.

When you look at the error codes, isent it a bit strange that there is both open circuit and short to positive on the same sensor, mabe both heater circuits acting uncorrectly and the scanner can't tell them apart?
Looking strictly at the scanner result its the front heater circuit that dosent work propperly as it always stays in ON condition, but i getting codes for the rear sensor only

This have given me many sleepless nights so if anyone out there have any information i would bee wery interested to hear about it

Arildoss
 

Andrew

A2OC Donor
Hi all
....
studied the workshop manual current flow diagram and i have found that they share the same earth connection (249, Earth connection -2-, in interior wiring harness) as the fuel pump relay but i can't find that connection, could anyone please tell me where it is?
......l
Arildoss
Good Evening,

Sorry I know little about your Lamda problem and cannot help but when I read your post and your plea for the location of the '249 Earth connection - 2 - ' it very much reminded me of a similiar plea I was making last summer for another earth connection '119 Earth connection - 1 -' in the headlight wiring harness. I was expecting it would be somewhere in one of the dozens of connector BLOCKS with multiple connector pins in the A2 wiring, but I was wrong. Turns out the wiring harnesses contain numerous so called WELDS and are normally out of sight hidden in the loom wrap, a picture of one I found down near the A-pillar.


As you can see the term WELD is confusing (in my opinion), not made by a welding machine and molten metal but a crimped connector made by some powerful press.

IF your elusive earth point is the same you will only find it by tracing back one of the wires in question, unwrapping the loom wrap as you go until you encounter it, but I would not bother I think it is unlikely to be the source of a problem, those WELDS are very solid.

Hope this helps.

Andy

Edit. A tell tale sign of a WELD within a harness is a bulge, you can certainly feel it with fingers.
 
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Arildoss

New Member
Thanks for quick and informative reply.

I think the same as you that it isent the problem. And as your describes it i don't think i will go any further with it and pull everything apart.
 
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