Codes P0131 and P0151

[etiger]

I see that these codes mean low voltage signals going to both banks of my O2 sensor. The car will sometimes not react when I try to give it gas and I will have to pull over and restart. This has only happened on long drive after I have been going for 3 hourse or so. Any ideas? Should I just replace the O2 sensor?

I recently changed out the fuel filter, but this error was occuring before I did that.

One finally comment, if I let the gas level go below a 1/4 tank and let it sit overnight it will not start the next morning unless I add alittle bit of gas to the tank. However, if you are driving you can drive all the way down to empty so I know it is not a faulty gauge, however, now I am wondering if these two issues are related.

Any ideas?
Thanks

[j cAT]

Originally Posted by etiger

I see that these codes mean low voltage signals going to both banks of my O2 sensor. The car will sometimes not react when I try to give it gas and I will have to pull over and restart. This has only happened on long drive after I have been going for 3 hourse or so. Any ideas? Should I just replace the O2 sensor?

I recently changed out the fuel filter, but this error was occuring before I did that.

One finally comment, if I let the gas level go below a 1/4 tank and let it sit overnight it will not start the next morning unless I add alittle bit of gas to the tank. However, if you are driving you can drive all the way down to empty so I know it is not a faulty gauge, however, now I am wondering if these two issues are related.

Any ideas?
Thanks

with a fuel pressure gauge measure for 60psi at the fuel rail test port...53psi min...the pressure should hold on shut down.

the fuel tank should never go below 1/4 tank....IF YOU frequently operate with low fuel you will have these problems...also the fuel filter is in need of replacement more often when running at the low levels ...replacement at 30,ooomi I have found works best,,,,as I cut open the filters in find they are 50% restricted at this point....


the O2 sensors require replacement at 100,000 mi....this is the recommended life as per manufacturer....If this is not done the cat's usually get damaged [no power]...............

exactly what year /engine do you have ? I'm assuming a 99-2005 5.3 L tahoe

[etiger]

Thanks! It is a 2004 5.3 with 108k. I will run the fuel pressure test, will a place like autozone do this for you or am I going to have to take it somewhere (or do I need to buy a gauge)?

I will go ahead and replace the O2 sensor. I am assuming this is a do it yourself job and is pretty easy to locate on the Tahoe?

[j cAT]

Originally Posted by etiger

Thanks! It is a 2004 5.3 with 108k. I will run the fuel pressure test, will a place like autozone do this for you or am I going to have to take it somewhere (or do I need to buy a gauge)?

I will go ahead and replace the O2 sensor. I am assuming this is a do it yourself job and is pretty easy to locate on the Tahoe?

when you replace the O2 upsteam sensors buy the exact same one's ..do not buy a sensor that has the wrong connector...

call for a parts store that has a fuel test gauge...I have my own so I don't know if they are able to do this...

[etiger]

Ok, I got a fuel pressure gauge and here are the results:

-with out the car running- 44psi
-with the car running- 42psi

Thoughts? I heard that the acceptable range is 40-60, is that correct?

I also bought 2 of the oxygen sensors, so there are 4 sensors total...my codes say that it is sensor 1 in both banks. Is sensor 1 on the driver side and sensor 2 on the passenger?

Thanks

[j cAT]

Originally Posted by etiger

Ok, I got a fuel pressure gauge and here are the results:

-with out the car running- 44psi
-with the car running- 42psi

Thoughts? I heard that the acceptable range is 40-60, is that correct?

I also bought 2 of the oxygen sensors, so there are 4 sensors total...my codes say that it is sensor 1 in both banks. Is sensor 1 on the driver side and sensor 2 on the passenger?

Thanks

as I stated ,,and on this issue here , on these forums it is stated many times , 60psi is the correct pressure.....53psi is the lowest that is barely acceptable.....

you simply must check the fuel pump ground point at the frame rail next to the tank....this means clean and reconnect...then measure the fuel pump voltage at the fuel tank to ensure it is getting the full 12++ volts DC...if this still causes low fuel pressure replace the fuel pump with a delphi pump.....if you use any other it won't last..

your O2 sensors .. do not install yet...after you correct the fuel issues ,,,,,if you get no DTC'S replace only the upstream O2 sensors,,,these require replacement every 100,ooomi..these control fuel management and will protect the cat ...this will also help on MPG,,,,.