O2 SENOR PROBLEM 4.3L

[JesseRogers]

On my 2002 4.3L Sierra Pickup (automatic extended cab) the "service engine soon" light came on. I ran the ODBII code reader and it responded with P0140 (post catalytic O2 senor no activity).

 

I replaced the O2 senor with an Autozone Bosch (four wire) and erased the code.

 

21 miles later, "service engine soon" light repeared and ODBII code read again read P0140. Check for loose connections, everything looks good. Erase code again, but it keeps coming back!!!

 

Any suggestions?

[citydriver]

Welcome to the Forum

Check the wiring harness past the connector to see if it rubbed thru anywhere

 

p.s...It 's an emissions problem..It may still be covered under the federal warranty

[Bent Wrench]

 

You need an AC Delco O2 senser! I see this kinda thing all the time.

[snoman]

Welcome to the Forum

Check the wiring harness past the connector to see if it rubbed thru anywhere

 

p.s...It 's an emissions problem..It may still be covered under the federal warranty

Yes if it is under 5yr/50,000 miles, it is covered

[muddog]

Bent Wrench, why can it only be an AC Delco?

 

 

 

I am having P142 code (bank 1 rich) thrown still after just replacing the EGR (like 2 days ago) and the O2 sensor on the drivers side (about a year ago), but Im not sure what brand it was...dont think it was an AC D. should I replace that O2 again with an ACD?? dont want to waste any more money

 

I have a 96 chevy 1500, 2wd, 4.3 with 91k

[rookie70]

On my 2002 4.3L Sierra Pickup (automatic extended cab) the "service engine soon" light came on.  I ran the ODBII code reader and it responded with P0140 (post catalytic O2 senor no activity).

 

I replaced the O2 senor with an Autozone Bosch (four wire) and erased the code.

 

21 miles later, "service engine soon" light repeared and ODBII code read again read P0140.  Check for loose connections, everything looks good.  Erase code again, but it keeps coming back!!!

 

Any suggestions?

 

<{POST_SNAPBACK}>

 

 

what method are you using to erase the "service engine soon" light?

[GMCSierra04]

Before you buy anything else, check the wiring to and from the o2 senor. First look for the obvious problems liek cut wires and then move into diagnosing. Make sure you have source voltage going to the connector whcih should be close to 5 volts and make sure you have return voltage going back to the PCM, range could be from 100mV to 900mV. Check these first before you get anything, but if you wanna buy something, get a Haynes or some repair manual with wiring diagrams. They will save you so much time! Good luck.