I just replaced my o2 sensor when i installed my a/f guage and now my car is throwing the code for o2 sensor. the wierd thing is that if the o2 sensor wasnt working then my a/f guage wouldnt work and it works fine, all connections are good. what could be causing this.

it only throws the code when its running

 

Check all the wiring from sensor to the ecu.

 

a/f guage is connected at the ecu the wiring looks fine

 

Put a meter on the 02 output wire and see if it's grounded out. Like grounded out to the shield that surrounds the output wire of the 02.

Is the connection at the 02 sensor a quick disconnect type??? Then disconnect it and start the engine. Put a meter on the output wire of the 02 and see what it's reading. It should be about .65vdc if you have no airpump or a disfunctional acv.

 

it shouldnt be grounding, there was no shielding on the old o2 sensor wire going to the plug, must not have been oem. and if it was grounded the guage wouldnt work anyway. is there a chance my ecu could just be screwed up?
i will try the voltage in the morning. also why does the code not show unless its running?

 

Your right. I should learn how to read and comprehend what I read.

Maybe disconnect the meter from the circuit and see what happens?

 

ya thats what i was thinking, it might be pulling the voltage or sumthing. i just wanted to do that last cuz i hate pulling the carpet up lol.
the guage is connected properly and connections are soldered so if you have any more ideas, shoot

 

What code does it throw?

 

5, one long light, long pause repeats. but like i said, only when its running

 

How did you tap into the O2 sensor wire? You might have accidentally cut the connection to the ECU.

 

i melted the insulation off a small spot at the ecu end, just enough to soften it the got it with my fingernail. then i soldered the guage wire onto it. never cut the wire

 

Try measuring the voltage right at the ECU pin, i.e. downstream of the joint. You'll see what the ECU's seeing. Make sure the engine and O2 sensor is at operating temp first.

Also double-check you did actually read the right code. Just in case...

 

ya i kept watching the lights, then i shut it off and started it again and got the same code. Im going to check the voltage in the morning then post an update, thanks for the help