Code for all 4 O2 sensors popping up

[Danie Lizarraga]

Hello everyone, i'm new to the forum. I hope someone can help me figure out what my problem is. I have a 2000 Tahoe z71 5.7 L, and I've never been able to figure out why all 4 of my O2 sensors go bad within a month or less. I've stopped buying new ones since almost a year and a half ago.

I've bought brand new ones and everythings good for about a month or less then the codes appear. I clear the codes and check after running the miles i need and nothing. Does anyone have an idea as to why I cant get the O2 sensors to stay good?

 

[OR VietVet]

Welcome to the forum from Oregon.

The rear O2 sensors can be dirtied up from cat problems. But I suspect that your ignition system is causing problems. How old are the plugs, wires, cap, rotor, fuel filter as well? Have you checked for vacuum leaks that would cause a lean condition and the sensors are richening-is this a word, the fuel mixture? Air filter? What brand and octane fuel do you run?


We recommend that you put all your rig(s) info in your signature so we all don’t have to guess at year, make, model, engine size, trans, rear axle locker…….etc. While you may have posted pertinent info in your first post, you may forget to do it again and the info is needed by us anyway. Makes it way easier on all members that attempt to help, to have that info right up front. It is also recommended that you take a pic of your RPO codes, on the inside cover of the glove box, and post that image in your signature. All this info will greatly help those that will try to help with a problem.


If there is any other info, like upgrades, mods or recent mechanical/maintenance work done, that would be helpful in any post as well. Too many times a question is asked by the poster and after about 10 responses we find out that the poster has done recent work to attempt to fix the problem or work that was done that SEEMS not related to the problem.

 

[wjburken]

Welcome to the forum from Iowa.

Looks like Ron (@PNW VietVet) has given you some homework. He’s an an old school mechanic and won’t steer you wrong. Others will likely chime in with some other thoughts as well.

 

[Fless]

It would be interesting to see the fuel trims, at idle and at 1500 or so RPMs. Bank 1 and Bank 2, long-term and short-term. If you have or can get a scanner, check those, jot them down, and post them up here.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

You've already got folks assisting you, which is great.

I hope that you will become a participating member in the Forum's discussions.

Pics, please.

 

[swathdiver]

Hello everyone, i'm new to the forum. I hope someone can help me figure out what my problem is. I have a 2000 Tahoe z71 5.7 L, and I've never been able to figure out why all 4 of my O2 sensors go bad within a month or less. I've stopped buying new ones since almost a year and a half ago.

I've bought brand new ones and everythings good for about a month or less then the codes appear. I clear the codes and check after running the miles i need and nothing. Does anyone have an idea as to why I cant get the O2 sensors to stay good?

Specifically, what codes are you getting?

 

[Danie Lizarraga]

Wow I wasn't expecting all the quick responses! thanks everyone for trying to help out so far. i currently have 5 codes, i figured the last code (P0410) was worth asking in this thread as well. I'm still learning how to use this forum so i apologize if a lot of information is missing. If i need to give any more information, do let me know. As for getting numbers while idling and etc that Fless has asked for, i will try and get them tomorrow as early as possible

As for the O2 sensor codes:
P0135
P0141
P0155
P0161

 

[Danie Lizarraga]

Welcome to the forum from Oregon.

The rear O2 sensors can be dirtied up from cat problems. But I suspect that your ignition system is causing problems. How old are the plugs, wires, cap, rotor, fuel filter as well? Have you checked for vacuum leaks that would cause a lean condition and the sensors are richening-is this a word, the fuel mixture? Air filter? What brand and octane fuel do you run?

I recently changed spark plugs and spark plug wires
Fuel filter is maybe a year old
The cap and rotor are a little over 2 years old
i run 89 octane
There are no vacuum leaks (at least that i've checked for)


The same time we changed the cap and rotor, we swapped in a remanufacture long block, but even before that we still had the codes from my post of the codes before.

The cats might possibly be the problem as they were changed approx. 9-10 years ago

 

[OR VietVet]

Sure does seem to point to that picture of cats and sensors. Post pics of the plugs when you can take them out and label them or keep them in order when you post the pics.

 

[Danie Lizarraga]

Sure does seem to point to that picture of cats and sensors. Post pics of the plugs when you can take them out and label them or keep them in order when you post the pics.

Would there be a way to tell if the cats are bad? Also the spark plugs are around 3 weeks old so i'll try to pull if it stops raining here

 

[OR VietVet]

Cats can get clogged and that may only show at certain times depending on the damage inside. A back pressure test is a good way or temp measurement from front to back after hot and temp difference side to side. Clogged exhaust can also give you a loss of power and bad vacuum readings.

This says it better than I can explain:

After the vacuum gauge is connected to a vacuum source, readings are noted at idle and then again at 2,500RPM. As engine speeds vary, readings should initially drop slightly, then rise to within 2-3" of the vacuum level established at idle. A large drop of 8-10" of vacuum typically indicates an exhaust restriction.

 

[afpj]

Did you check fuses? I think with my 2002, there's a specific fuse for the heater circuit for the O2 sensor

 

[swathdiver]

Wow I wasn't expecting all the quick responses! thanks everyone for trying to help out so far. i currently have 5 codes, i figured the last code (P0410) was worth asking in this thread as well. I'm still learning how to use this forum so i apologize if a lot of information is missing. If i need to give any more information, do let me know. As for getting numbers while idling and etc that Fless has asked for, i will try and get them tomorrow as early as possible

As for the O2 sensor codes:
P0135
P0141
P0155
P0161

View attachment 256247 View attachment 256248 View attachment 256249 View attachment 256250 View attachment 256251

That's what I thought, you might have a wiring problem. A critter may have chewed through some wires further up along the wiring harness. If all that looks good, it's time for a new engine computer. If you wiggle the wiring and the values change, then it's wiring. If not, computer time.

 

[Danie Lizarraga]

Thank you everyone for the advice i will check on all these things after the rain is gone

 

[OR VietVet]

 

[JEFFC]

The o2 codes that you have are all for the heater circuit, not the actual sensor circuit (that would be different codes). A bad o2 heater can cause the codes that you have but the chances of all 4 going bad at once is nearly impossible. Do not replace anything until you verify that the heater circuit is good, Start with the fuse. All that the o2 heater does is allow the o2 sensor to warm up faster, giving the computer a more accurate reading during the first few minutes of operation. The heat of the exhaust keeps the sensors hot within a few minutes of starting and the heater is no longer needed. The other code that you have has to do with the air injection system which also only runs during a cold start and is monitored by the o2 sensors. Disregard the air injection code until the o2 problem is solved. Since you have the 5.7L engine in a 2000, that would indicate that you have an old body style Tahoe. There was a mid year change in 2000 to the new body and 5.3 engine. To avoid confusion when doing an internet search, plug in 1999 Tahoe instead of 2000.

 

[Danie Lizarraga]

The o2 codes that you have are all for the heater circuit, not the actual sensor circuit (that would be different codes). A bad o2 heater can cause the codes that you have but the chances of all 4 going bad at once is nearly impossible. Do not replace anything until you verify that the heater circuit is good, Start with the fuse. All that the o2 heater does is allow the o2 sensor to warm up faster, giving the computer a more accurate reading during the first few minutes of operation. The heat of the exhaust keeps the sensors hot within a few minutes of starting and the heater is no longer needed. The other code that you have has to do with the air injection system which also only runs during a cold start and is monitored by the o2 sensors. Disregard the air injection code until the o2 problem is solved. Since you have the 5.7L engine in a 2000, that would indicate that you have an old body style Tahoe. There was a mid year change in 2000 to the new body and 5.3 engine. To avoid confusion when doing an internet search, plug in 1999 Tahoe instead of 2000.

I just checked the fuses with a volt meter and they are good, it has a 30 amp fuse instead of a 20. I don't think it would make that big of a deal would it?

and yes i do have the old body style tahoe

 

[JEFFC]

Sorry for the delay, kind of crazy around here with all of the fires. The 30 amp fuse will not stop the circuit from working. The higher than rated fuse could indicate that the previous owner was having a problem with the circuit blowing fuses and tried a larger fuse. The larger fuse could have caused the previous short to fry and is now an open circuit. You need to find a mechanic that is good with electrical and trace the system.

 

[Doubeleive]

I would check that 02 heater circuit with a meter, @swathdiver do you have the info for the 02 heater circuit on a obs? ohm's check?

 

[swathdiver]

I would check that 02 heater circuit with a meter, @swathdiver do you have the info for the 02 heater circuit on a obs? ohm's check?

Don't think so, will check after work. If all the wiring checks out it's probably the ECM.