RTV (silicone) posioned O2 sensor

firsthere said:

I cannot tell which, the only pair with a measurement from the Ohm setting.

Click to expand...

rockola1971 said:

Heres a schematic for the 04 Tahoe. The symbol on the left of each sensor with the diagonal arrow pointing up and to the right are the actual 02 sensor of the whole sensor. The squiggly symbols to the right of each sensor element are the heaters. So just look at the wire colors and measure across the correct pair at each sensor. Each heating element circuit will have a pink wire on one side of the element. Just touch your meter the corresponding on the sensor, etc. (with wiring harness unplugged from sensor).

Fun Fact: The heater part of the sensor is fed power(12v+) by the 15a fuse directly to the sensor heater on one side. The PCM provides the ground on the side. ON the 02 sensor part of it the PCM provides power and ground for each side of the sensor part.

Click to expand...

firsthere said:

Replaced both upstream sensors with unbranded ebay units. I figured if they were to contaminate again I'd rather be out just a few bucks. I already have AC delco sensors ready to go in if, when, needed.

Anyways, the sensor must have been the problem with the short as the new ones do not blow the fuse. It Is getting a latent P0171 (bank 1 lean) with No CEL. The idle is smooth and truck runs well though. Fuel trim on bank 1 is in the lower double digits so I will re-torque the intake and check all lines and sensors fittings. Could also be the new ebay O2 units I guess.

Just for reference, by Comparison of the new ebay sensors which were at 6.2 each and both original downstream sensors (still in use) are around 12 Ohms, Should that be a concern at the higher end service range (16 Ohms max) thus need to be replaced as well? Also, does the static O2 sensor resistance change fuel trim enough to worry about as long as its within the service range...

Click to expand...