Purchased Bosch OE replacement O2 sensor mid June 2007.

I've had a code 41 ever since installing it.

#3 and #4 terminals show 11.54VDC. #1 and #2 terminals show 0.04VDC.

No continuity between #1 and #2, but my meter is reading 1,895 ohms when it should be between 10 and 40 ohms, between #3 and #4. I just rechecked it and read 1,950 ohms.

I had to put my meter on the 2,000 ohms range to get a reading.

Does anyone have any idea what in the world is going wrong here, a glance at the connections on the passenger strut tower seem ok, but slightly to extremely dirty where the wires come from the engine harness to the connector, to the connector block.

Thanks in advance for any troubleshooting guru that can help!


Modified by LawlessOne at 7:21 AM 8/11/2007

 

Are you measuring from the sensor end of the plug or the ECU end?
Female end is the ECU side while the male end is the sensor side.

Female plug end terminals 3 & 4 should read 12V with ignition switch ON. Terminals 1 & 2 goes to the ECU so you will not get any DC voltage reading there.

On the sensor plug, Terminal 3 & 4 should read about 10 - 20 ohms for the heater element. Terminals 1 & 2 has zero resistance.

O2 sensor only generates DC signal when up to operating temp. (0.01 to 0.9Volts)

 

I've checked both.

Engine harness end is what I posted ( I believe this is what you are calling the ECU side )

I get nothing on the sensor side, meaning NO resistance, No continuity. I didn't warm the sensor up first though.

I think the sensor is bad, even though it is brand new. The code started as soon as I put the new sensor in. The CAT only has about 2x,xxx miles on it, and 41 ( four long, one short ) is the only code I'm getting.

According to the Haynes ( which I'm not crazy about ) the resistance of the sensor should be 10 - 20 ohms for a 91 - 92 Accord and 10 - 40 ohms for a 93 Accord.

This should mean that out of the box, the resistance should be at least 10 ohms.


Modified by LawlessOne at 12:37 AM 8/12/2007

 

Nevermind, faulty O2 sensor.

Returned, Replaced, Running.