O.k...so i got a code...left 02 sensor lean. So i throw up freescan check the voltage, and it won't go over 4 mv. So i replace them (since they are the origional sensors with 118,xxx on them) and check it again...it throws it again. It's still at 4 mv. Anyone had this problem before? I checked the wiring harness and their is no damage that i can tell of. Also, this happened after i installed my long tubes....

 

Anyone?

 

I have the same problem but havn't fixed it. I also checked the wires and connectors for damage and still have gone through new o2 sensors. I know I don't have any exhaust leaks either.

 

do you have 5 volts at the connector give or take a little?

Z

 

is there any oil or anything getting on the plugs for the O2 sensors? I had an oil leak and the oil got doen into the plug and messed up the sensor.

 

Did you use harness extensions when you added the long tube? Check the extensions for a broken or shorted wire.

 

I did have the line to an old oil pressure guage break from the secondary outlet down their the first day i had the long tubes. Whats the best way to clean that? I know it isn't the extensions. I extended the wires on old ones the first time, and then when i bought my new ones i bought extentions.

 

Which wire should i have 5 volts at?

 

I am pretty sure they run off of 5 volts. Unplug the sensor, and with the key on, check the 4 wires for voltage. Sorry I can't remeber which one/s should have voltage. I'm sure someone on here should know. Sorry I'm not giving great advice. If it isn't 5 volts, then its 12 volts.

Check out this schematic:

http://shbox.com/1/HO2S_connector.jpg

Z

 

The sensor heaters get 12V on the pink (+12V) and black (ground) wires.

The sensor element itself has a ground (tan wire) and a signal wire (purple or purple/white). The PCM sets a bias voltage of 0.450V on that circuit and the O2 sensor adds or subtracts from that voltage making it range from 0V to 1.0V.

To my knowledge, there is no "5V" circuit to the O2 sensor.
One more try.... did you check the extension? Just because its new doesn't mean its "OK" or that it didn't get damaged at some point. Would seem to me that it would be a good idea to check the continuity on each wire in the extension. Or, if physically possible, swap the extensions left to right and see if the problem follows the extension. At least that way you would rule out the extension.

 

Sorry, I knew it was either 5V or 12V. Thanks for the clarification.

ZMAN

 

I'll try that, but i had the old ones hard extended with wires and now the new ones with extensions and they same problem....i'm going to check but i have sorta ruled that possibilty out

 

I know this is an old thread... but I was just curious what the fix was. I am having the same exact issue on my car. Same side of the engine bay. New sensors as well.