o2 high voltage (please help)
Thread Starter
Teching In
Joined: Jun 2006
Posts: 23
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o2 high voltage (please help) I have a terrible misfire that ive been trying to get fixed for a while now. First it was a bad o2 senser so i replaced it. Then it was the other o2 senser so i replaced it (i dont have rear o2s). Still no fix. Then i did plugs still no fix. I had a missfire code and still the same o2 codes and a mil lamp code.
Well after about a week of it sitting i had the codes ran again and this time it was bank 2 senser 1 high voltage. So i switched the o2s around to see if the code followed and it didnt so the sensers are fine. I ran the wires up to the pcm and it looked fine to me. They are very close the the headers but it has that plastic on em with heat rap. What should i do/look for.
Any input at all is very appreciated.
Dan
Well after about a week of it sitting i had the codes ran again and this time it was bank 2 senser 1 high voltage. So i switched the o2s around to see if the code followed and it didnt so the sensers are fine. I ran the wires up to the pcm and it looked fine to me. They are very close the the headers but it has that plastic on em with heat rap. What should i do/look for.
Any input at all is very appreciated.
Dan
On The Tree
Joined: May 2005
Posts: 132
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From: North Carolina
High voltage means the PCM is seeing a voltage above 450mV for an extended period of time. This means one of two things: Bank two is running really rich, or the Sensor Signal wire is shorted to voltage somewhere.
A quick test would be to monitor B2S1 voltage with a scantool, then unplug the sensor. If the reading defaults to 450mV, then you have a rich condition. If its does not, then you have a short to voltage.
If its a short to voltage, unplug the PCM connectors and see if they are corroded or full of water.
If its a rich condition, you may have a stuck open injector (hence the misfire). You could raise the fuel rail off the intake and turn the ignition key on and see if any injectors drip/spray fuel (they should not).
A quick test would be to monitor B2S1 voltage with a scantool, then unplug the sensor. If the reading defaults to 450mV, then you have a rich condition. If its does not, then you have a short to voltage.
If its a short to voltage, unplug the PCM connectors and see if they are corroded or full of water.
If its a rich condition, you may have a stuck open injector (hence the misfire). You could raise the fuel rail off the intake and turn the ignition key on and see if any injectors drip/spray fuel (they should not).
Thread Starter
Teching In
Joined: Jun 2006
Posts: 23
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i know this a complete noob question but how do i go about checking the pcm connections? What i mean is how do i take it off and/or apart?
Thanks alot for the help SUPRLYZ its greatly appreciated!
Dan
Thanks alot for the help SUPRLYZ its greatly appreciated!
Dan
Launching!
Joined: Apr 2004
Posts: 230
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From: south jersey
im having the same problem... at wot the car will run fine.... but that that misfire comes around at normal driving... it goes on and off... says i have 02 problems like circuit low volts on both sensors.... dont know what else i can do to try to fix it.. .
