New Idle Problem - Next Steps?

[ausgezeichnet]

OK. Either my O2 sensor is shot or I need more help.

Here is a picture of my O2 sensor disconnected. With the car running and up to temperature

1. I got a reading of just under 12V with he leads on the red and green pins. (the part of the connector that covers the pins was broken off so I removed it to make the picutre clearer)

2. With the leads on the yellow and blue, I could not get any reading what so-ever.



Later when I removed my O2 sensor, the tip of the sensor that is inserted in the Cat was dark gray/black in color.

Any Suggesstions? Thanks.

[Lorenfb]

Your O2 sensor is a 4 wire type with two of the wires for the heater.
You must have the heater working or the engine very hot to get a
reading from the other wires (actual O2 voltage).

[ausgezeichnet]

Loren,

I double checked and I only have 3 wires on my O2 sensor. The Bentley manual also says it has 3 wires. One for the signal (black), one for the heater circuit power (white) and one for ground (white).


What may be confusing is my picture. The red and green terminals are really the insides of the female part of the connector that the yellow and blue terminals are inserted into. On my car, the outer housing of the female part of the connector cracked off.

As you can see from the picture the two wires that go into this connector are white. This means they are the ground and the heater power. In your instructions, I should be testing the voltage of the signal, correct? This means I should be testing the black wire. Does that make sense?


Thanks for all your help.


-Mike

[jtcmuga]

Mike,

Hey, my O2 sensor heater harness was cracked up, too... I doctered it up with some shrinkwrap and electrical tape. The 12v you're seeing is verifying that the heater is getting power. That's good. I want to say that 13.6v is what you're looking for, though. I'll get back to you on that. I wasn't taking any chances with my sensor, so I just replaced it. After all, it is a 30k mile part... and another check-off on my troubleshooting list...

Good luck,

Jojo

[ausgezeichnet]

Jojo,

Thanks, I am quickly coming to that same conclusion to just replace it. My Carerra has 138K miles on it, is 20 years old and based on how hard the 02 sensor was to remove and the condition of the 02 sensor, it may be the original sensor.

I was doing a little research on 02 sensors last night and I found a few sources that sell the Bosch OEM 02 sensor with out the connectors for ~$80. The same Bosch OEM 02 sensor with the connectors was $180-200. Does any one know why I should not try and reuse the existing connectors and save $100 bucks?

[jtcmuga]

Mike,

Sorry I didn't add this to my last thread... I installed the later Carrera O2 sensor. It doesn't have the same connector, but it still has the same three wires... so I just used the old connectors. I paid ~95 bucks for it. My plan is to check salvage areas to find the connector from the later Carreras and install that so future O2 sensor replacements won't require splicing wires.

Save yourself some cash, you're gonna need it for tires :-)

Jojo

[scottb]

There's been lots of discussion on the board about the pros and cons of the generic O2 sensor vs. the P-car specific 02 sensor. Personally, I bought the generic one, soldered the old connector on to the new sensor, shrink-wrapped everything, and it's been rock-solid since it was installed.

[ausgezeichnet]

Thanks for the feedback guys. I found this thread which was very helpful.

O2 Sensor.. Alert ! ..and new info