Bank 2 (Radiator side) Upper HO2S Sensor Heater Circuit Malfunction (HO2S-21)
To the left of the red arrow in this picture is the O2 sensor in question. On this 2-D image, the sensor is partially hidden by the front "frame". Note you might have to remove the front radiator deflector to get to it. 22 mm crescent wrench (or 7/8 inch) or a O2 sensor removal tool ($10 at Advance or Autozone).
Originally posted by chongo:
The easy things to do are to check for
�· Blown fuse in the fuse box.
�· Check for broken or chafed wiring from the sensor to the connector (probably blue or green color connector) and connector to PCM (under the Power Steering Reservoir at the passenger side strut)
�· If there appears to be water in harness connector, use hair dryer to dry it, spray some WD-40, wipe it dry, reconnect and then tape over with duct tape (to prevent water from getting to it)
�· Also check to make sure PCM connector is not loose or wet.
. You may actually just want to put in a new O2 sensor. (about $70) but if you want to test that is fine too.
First Test
1) Disconnect the 02, but leave the battery connected
2) Measure the resistence between the PWR and GRND terminals of the sensor. it should be approx 6 ohms at 68 degrees F.
Second Test
1) With the sensor connected and the engine running, measure the voltage between the H02S and SIG RTN (Ground) of the 02 sensor. voltage should fluctuate between 0.01-1.1 volts.
If the first test doesn't read around 6 ohms, or if the second test yeilds slow fluctuation or voltage isn't within specification, replace the sensor.
