I erased the trouble code, and so far the "check engine" light has stayed off over several days of driving - is this a sign that the problem was a transient one, at least for the moment? It'd be nice not to have to spend time under the car right now, since I don't have a garage and it's rainy season (and not to have to spend the money for the part!).

Hello,

I have a 96 turbo wagon and the exact same error message. It was on when I got the car (about 117k miles). I could not bring myself to buy the new o2 sensors yet $$$.

-hp

You have to be careful when measuring votage on an O2 sensor. It is best NOT to disconnect to test it. If you need to see how the sensor reacts in a "live" situation, it is best to TAP the signal wire then induce a simulated lean A/F mixture by loosesning a vacuum hose while watching the voltmeter, the voltage should drop and stay relatively low until you reconnect the hose. You might want to spray a little carb cleaner into the intake and then watch the voltmeter to verify the voltage goes up and stays there until you stop spraying. These simulations should cause a change in front O2 sensor voltage about 1-2 secs. after inducing them.

Just letting you know that there are two sensors and the cheapest I found was $185 each at IPD. Hence it may not be worth changing them unless you are certain of the problem.

Are you getting a "front" (Bank 1) or "rear" (Bank 2) indication? Are the sensors the origionals? If so, on a 96 they're suspect. You can look over in the 700/900 FAQ section for info on trouble shooting them. If you have a digital VOM, set it to the min. voltage setting ( 1v or sometimes 3v) Unplug the 02 sensor connectors (bay 13 has photos) as they're a pain to reach. Each has four wires (black, gray and two white) with the black wire being the "hot" or signal wire. Hook your + VOM lead to the black wire pin and the - lead to ground (hook to the wire coming FROM the sensor). Start the engine and watch the reading. A good front sensor will show a voltage of about .25-.75v and the reading will fluxiate constantly and rapidly. If it doesn't it's probably bad. The rear sensor will read about .25v or so and be fairly constant.

bl