02 sensors without a signal

[Haziness8]

ive had the code p0174 (bank 2). usualy problem is solved by new 02 sensors, cleaning MAF sensor, or fixin vacum leak. ive done all this but still no fix. i recently tried using a friend's full detailed scanner and revealved that my comp. reads nothing from my 02 sensors. ive replaced all four so they cant be bad. anyone ever seen this, ive tried searching forum but i got nothing. help

 

[ExplorerDMB]

Did you make sure you reconnected them? When you say "no signal" what do you mean exactly? The normal fixes aren't always the actual "fix". I would look at your fuel pressures. Make sure you are getting the correct pressure to the rails. There are many things that can cause a lean issue, do you have a SOHC?

-Drew

 

[Haziness8]

yes i have a SOHC. i meant that the computer was not reading any eletrical signals from all four sensors, no voltage or watts im not sure what it is. i reconected them all. its strange that all four would not work, must be some deep electrical prob maybe?

 

[BrooklynBay]

I wonder if there is an actual computer problem. I've had similar problems working on GM cars. They use a PROM chip. In one vehicle, it kept showing that the map sensor was bad even though I replaced it. Another vehicle kept showing an intermittent check engine light, with codes, even though the sensors were replaced. Disconnecting the battery didn't reset them either. The newer vehicles require a scan tool to reset codes. Do you have another computer to swap into this to see if you will get the same faulty reading of no O2 sensors?

 

[Runnin'OnEmpty]

There's an O2 heater circuit fuse in the fuse box under the hood, that feeds all O2 sensor heaters. Generally theres another code set if this fuse is blown or open, but might be worth a look.....

 

[Haziness8]

checked the fuse, its fine, 02 sensors still are all failing.

 

[BrooklynBay]

Even though the fuse is good, I would still check the wiring to see if there is power going to the heaters on the O2 sensors. The computer only activates the heaters when the engine temperature is low. They stop heating a few minutes after the engine reaches a predetermined temperature. I'm not sure exactly how may degrees the engine has to be, but I know that they don't continue heating when everything is already hot.