dtc13: OPEN O2 SENSOR

I do not use my TS very much now ...but last year, fuel burn suddenly got excessively high..but then TS was hangared for the winter. Back on the road this summer for a few occasions, the same proved evident. My suspect was the O2 sensor...but no CEL. SO checked by flashing the codes yesterday, and got a DTC13: open O2 sensor. It figures. And DTC13 does not light up the CEL...
No investigation yet.......at this time I have a temporary medical condition that impairs my activities...I still suspect the wire bundle entering the computer: several individual wires there have been severed in the past years....
THe fuel mixture is so rich (DTC13 keeps in open loop mode) that increading throttle fouls the spark plugs and the engine then runs on less than 6 cylinders.
So...TS at rest for a little while. WIll report findings later.

www.avigex.ca/xport/dtc13a.jpg
www.avigex.ca/xport/dtc13b.jpg

What you have to determine, is it the sensor or is it the harness back to the ECM or the ECM itself?

About the only way to know for sure is with a scan tool.....with key on, attach a jumper wire to the harness end going to the ECM, not the sensor.....with nothing touching the end of the jumper, scan data for O2 sensor should be .455....now hold the end of the jumper with one hand and with the other hand touch the neg bat terminal....voltage should drop to zero....now touch the pos term and it should go to approx 1 volt....if you get this, the harness and ECM are ok, and you need a sensor.......

Voltage from ECM verified OK at connector C111 contact C2. Have now to check for continuity down to the sensor....
According to the shop manual, the O2 sensor connector shoud be near the top of the rear valve cover...but could not find it yet. has Anyone ever seen it ?

OK I found the sensor and the connector by hand feeling....laying over a carpet over the engine ...
invisible to the eye and unable to disconnect at this point....
more later

By the way, I have disconnected the battery in the hope that bias values installed in the "mixture/injection control" return to default values. THe recent history indicates that false O2 readings have biased the control to an extra rich value....leading to catastrophic fuel burn and spark plug fouling. I remember that last year, I have had a lean DTC code..which may have trigged a bias toward rich. . IN the immediate, if I need the car in a hurry and the problen has not been corrected at the source, I will tweak the O2 return to a "rich" value, so that the bias will have a tendency to lean . Electronically speaking, this is easy...a high impedence feed at C111 contact C2 in the area of 0.7 volt will do the trick. (over 0.75v it would pop a too rich DTC code) . A simple voltage divider will do it. NOt a long term solution..but OK for short term. As described, the computer expects the O2 return voltage to fluctuate...otherwise it understands something is wrong....so I'll see what I will do about that too.

You have to do my test right at the connector to the O2 sensor.....

Has the O2 sensor ever been replaced?

www.avigex.ca/xport/dtc13a.jpg and www.avigex.ca/xport/dtc13b.jpg tells exactly the expected values and being expert in electronics, no problem in interpreting them. At this time,my problem is purely accessibility: the connector is located , but invisible deep between the engine and the firewall , so am unable to perform the disconnect and other unwanted priorities take my time. It will take a little time but will report findings as they come.. Of course checking continuity is a necessary step,
SOme years ago when I went for the rear spark plugs from under, the O2 sensor was seen as more accessible from that position ....
O2 sensor is original.

With excessive lighting and body contorsion, with the help of mirrors and dedication in achieving the duty.....I have been able to grasp and disconnect the sensor. Conduction from ECU to sensor output OK..but sensor heater (contacts A B) shot....

There is no heater circuit on this O2 sensor....

Obviously.....this is a heated O2 sensor

http://www.avigex.ca/xport/fuelinject.jpg

p.s. my bandwidth exceded...will return OK on sep 1

My bad....didn't think that year had a heater circuit, but it does....

Hi everyone
One year later...no much change. I drive a Kia Sorento now but still keep the TS. I have procured the O2 sensor from ROckAuto but no urge to change it. In fact, I have replaced the front 3 spark plugs (easy) in hope I got rid of the fouled plugs but obviously the rear ones are still keeping the engine from turning smooth..so at this time, since it can hardly go on the road, I have not got the time or patience to reach the rear plugs and O2 sensor. Some are able to replace the rear plugs by crawling over the engine...but I can't. I have done it before from under the car
http://www.automotiveforums.com/vbulletin/showthread.php?t=599442
and it would also make the O2 sensor accessible....SO..it will rest as is for the coming winter...will see next spring.
Against my wife's wishes....I keep the TS, that I consider the best car I ever had.