From digest.v7.n35 Fri Aug 1 15:18:55 1997
From: ILESQ_at_aol.com
Date: Fri, 1 Aug 1997 14:23:22 -0400 (EDT)
Subject: <e28> o2 sensor follow up

Following up on my earlier post, I will summarize what I have learned:

1. Although a digital meter is optimal, you can get a rough idea of your sensor's condition from an analog meter. If working, the needle will jump up and down from .2v to .9v. My old sensor went from about .2V to nothing, clearly bad.
2. A good place to read the sensor is a green wire which is connected to a white connector with a black rubber boot which protrudes from the main harness bundle near the oil filler cap. (BTW, does anyone know the function of this connector? It is not just a plug - it appears to contain a resistor or at least have resistance from one side to the other.)
3. I was able to get the old sensor out without too much trouble with a crescent wrench, with the car on the ground, after pulling off the snap on heat shield. The new sensor comes precoated with antiseize.
4. Regarding substitution, Bosch lists #13942 as its interchange for the Ford DY606 that others have recommended, and is cheaper. Cheaper still, and apparently identical to the 942 except for the connector which will be cut off anyway is 13913, whose original application was an 86 Taurus V-6, (I paid about $44 for it). This is even less than some of the kits available by mail order and given that the original application is as common as dirt, it should be in stock at any auto parts store in North America that sells Bosch. (BTW, both of these sensors appeared the same as my (literally) factory original at the tip, but the barrel was somewhat shorter) At this price, there is no reason not to change your sensor every 60,000 miles, which is Bosch's current recommendation, especially since you will get your money back in increased mileage fairly quickly- see below.
5. I notice an immediate increase of about 2-3 mpg after replacing the sensor.