"The service engine soon light does not come on even thought the O2 sensor is disconnected. Tthe wire has broke off at the sensor."
From the 87 manual: if the engine is at
| normal operating temp. |
| at least 2 minutes after engine start |
| O2 sensor voltage steady (it is steady with the O2 sensor open) |
| Throttle above 7% |
| All conditions met for 60 seconds |
THEN the system will set a Code 13 (open loop) and will not go closed loop.
From: Oliver Scholz
I just got back from Engine Performance Lab, and guess what we were talking about....oxygen sensors. The professor says that there are four things that "kill" and oxygen sensor: leaded fuel, silcone (use gasket sealer that is O2 safe), antifreeze, and additives in motor oil. I never realized it until today that the O2 sensor gets reference from outside air, it "breathes" through an opening around the wire that goes to the computer, so if the wire is tape up around the sensor, it will read full rich. So if any of the above substances get around the wire of the O2 sensor it destroys it.
From: Karen Nordling
The ECM supplies a voltage of about .45V between the ECM's B2 and B23 terminals. (B2 goes to sensor, B23 goes to ground) If measured with a 10Mohm DVM, this may read as low as .32V (use a high impedance digital meter, can be measured right at sensor).
The O2 sensor varies the voltage within a range of about 1V if the exhaust is rich, down to .1V if the exhaust is lean. The sensor is like an open circuit and produces no voltage when it below 360C (600F). An open sensor circuit, or cold sensor, causes "Open Loop" operation.
A good sensor should have a steady output voltage between .3 and .6 volts - test conditions: engine has reached normal operating temperature (above 80C), ignition on, engine shut off.
A lean condition is logged if voltage remains below .2V, and rich is logged if voltage stays above .7V. An open circuit is logged if the engine has been running in closed loop mode and the voltage is in the .35V to .55V range with a throttle angle above 7%.
From: Lance Osborne
The O2 sensor is designed to generate a voltage between 0.1 volt (lean) to 0.9 volt (rich). Code 44 can only be set if the output from the O2 sensor remains below 0.2 volts for longer than 60 seconds, which is normally not an operating condition of the vehicle.
If the problem intermittantly occurs, I would make cure that your O2 sensor wire is not shorting to the engine or something else underhood. If it always occurs, then your sensor is likely bad and in need of replacement. If you have not changed your sensor in the last 20,000-30,000 miles, it's probably due for replacement anyway.
From: Bret Scott
There is a special socket that I paid $10 for this weekend that has a slot on one side for the wire. If I didn't have so many cars with oxygen sensors, I wouldn't have bought it.
From: Robby Sperr
The sensor is located in the middle of the exhaust manifold, it looks like a spark plug with a wire coming out of it. Get some liquid wrench pentrating oil. With the engine cold, squirt some of this on....get a beer....drink it. Now that the liquid wrench has had time to work.. unplug the oxygen sensor, just a simple single connector. Next get a 7/8" wrench and remove the sensor. Like a spark plug basically. you may have to give the wrench a light tap (with a hammer) to loosen the sensor. A sharp tap with usually loosen a stuck bolt better than try to use lots of pushing or pulling on the wrench.
With the sensor out. Replace it with a AC one...$35. Make sure they have the anti-sieze on the threads, if not, go and buy some of, it should come in a tube. This will make the removal easier the next time. Tighten the new sensor up and hook up the wire. make sure the wire it not touching the exhaust anywhere.
From: Jason Wenglikowski
I changed the O2 sensor on my father's 85 GT and it was a breeze...easy as the 4cyl! I just used a 7/8" open ended wrench and I had it changed in a few minutes. I got it from the top. Under advice from Rich Delzer and GM, make sure the O2 sensor has anti-seize compound on it, if not put some on. The AC part comes with it on the threads. This will make the next O2 sensor change a breeze again.
From: Jason Wenglikowski
