O2 sensors

**bdford** · 09-08-2007, 01:24 PM

My engine light is on and the codes read that all four O2 sensors are bad. I hollowed out my cats and I havent replaced my O2's. Is this affecting my A/F ratio or my performance?

**mrr23** · 09-08-2007, 02:31 PM

all four? usually when you gut the cats, it'll throw the codes for both rear o2s. did you plug all the sensors back in?

**sreve** · 09-08-2007, 03:52 PM

an O2 code does not nessasarily mean its bad. there are alot of O2 codes.
which ones do you have?
rubbed wires or a blown heater fuse is not uncommon.

**2001NBMZ28** · 09-08-2007, 04:15 PM

When you say haven't replaced the 02's you don't mean the fronts also right? Make sure the fronts are plugged into the right connectors too. An exhaust leak near an 02 will also throw codes.

**35thAnniZ28** · 09-10-2007, 10:38 AM

yup prepare for the richness and loss of mpg... ok solution will be ...headers,y pipe and a good effing tune...and your car is back where it was but alot more beefier ...its worth it

**0rion** · 09-11-2007, 08:54 AM

first post up what codes you have

**Justin23454** · 09-19-2007, 07:44 AM

I have the same thing but says its my back 2. Ive done nothing to the car as of yet cept for a new lid. Also I have noticed im gettin alot less MPG. Should I just replace them? (I took it to autozone and they told me its the rear ones)

**ladunnkity** · 09-26-2007, 03:49 PM

hey im having kind of same problems. y-pipe,rear o2 delete getting codes p0131 nad p0151 for both o2 sensors. just replaced both with new ac-delco and took it out to drive and both codes came back. any thoughts. seems like it is really lean and stumble at low rpms.

**0rion** · 09-26-2007, 04:53 PM

Originally Posted by ladunnkity

hey im having kind of same problems. y-pipe,rear o2 delete getting codes p0131 nad p0151 for both o2 sensors. just replaced both with new ac-delco and took it out to drive and both codes came back. any thoughts. seems like it is really lean and stumble at low rpms.

those are lean codes for the front sensors. Have you checked your fuel pressure at the rail? Any leaks in the exhaust before the front O2's? A.I.R. pump working properly?

**ladunnkity** · 09-27-2007, 07:57 AM

no exhaust leaks that i can find, A.I.R was delted from computer also. checking pressure tonight.

**ladunnkity** · 10-04-2007, 04:44 AM

Well When I First Start It Up Goes Right To 43 Pounds But As It Sits There It Slowly Drops Down To About 22 And Starts Bucking And Dying. So I Guess I Need A New Fuel Pump. Any Recomendations And Does Anyone Know What The Difference Is Between A 98 And 99-02? Thanks

**0rion** · 10-04-2007, 04:54 PM

yeah, I highly recommend a racetronix kit from Harris Speed Works ( sponsor). Matt is great to do business with. There's a thread on HSW in the sponsor feedback section right now.

The 98's have metal tanks with baffles and the 99+ have plastic tanks with the pump sitting in a bucket and a venturi feed to the bucket.