P0137 Oxygen Sensor Circuit Low Voltage (Bank 1, Sensor 2)
P0138 Oxygen Sensor Circuit High Voltage (Bank 1, Sensor 2)

P0157 Oxygen Sensor Circuit Low Voltage (Bank 2, Sensor 2)
P0158 Oxygen Sensor Circuit High Voltage (Bank 2, Sensor 2)

From these codes I'm going to say it's not the sensors themselves. There is a grounding issue somewhere.

Check your battery and make sure positive and ground are tight. Any other electrical issues with the car at all? Anything?!

After that you might want to consider upgrading the "Big 3" or at least upgrading the battery ground cable.

Otherwise, get the car on a lift or on jack stands and get under there and trace the wires. Where do they ground to? How do the wires look? Any corrosion?

One other thing to consider is that your car could be running lean or rich causing these errors. Might want to get a leak down test done. How's the coolant? Have you changed the oil lately? How did it look?

Have your MPG's taken a hit lately? etc. etc.


Hope this helps.

 

As far as any other electrical issues goes, every now and then the rear power windows do not function. Sometimes it's the rear right, sometimes the rear left.

The oil looks fine. Have always done regular oil changes myself and have always inspected for impurities. Coolant is also top notch.

As for fuel economy, I have noticed that it has started to dwindle lately...

Please forgive my ignorance but what it the "big 3" ?

Thanks

 

Big 3 are the main grounds. Alt ground, Battery ground and Trans ground.

If you have other electrical demons... I hate to say this but it could be the BCM or PCM. I would be interested to know if the signals for the o2 sensors run through the BCM.... Anyone know?

Right now I'm gonna say you have a BCM issue or something is going on in your motor.

Are you running a tune via DiabloSport or some other company?

 

Nope, no tune or mods (yet..)

Would an faulty EGR cause a high and low voltage code for the post cat O2's?

 

Oh **** this is the 3.5

Yes it could possibly be the EGR..... I really need to think while I'm reading... lol

 

I'm going to replace the EGR valve and check the ground wires.
Will keep you posted. Thanks for the advice Mahalo

 

Well.. I chenged the EGR valve and besides the engine running like new, it did not take care of my problem with the post cat O2 sensors...

Does anyone know how to run a diagnostic on them?

 

I have seen issues before on aftermarket o2 sensors. I had a Chevy in my fleet that went through a hand full of aftermarket sensors before we went factory and the problem never came back. My concern in this case is all 4 sensors going at one time leads me to beleive that there is something upstream causing the problem. The o2's only monitor the exhaust. All of the diagnosis for this issue start with checking for a short to ground- then o2- then PCM.

 

Hi, thanks for your responses and sorry for the delay.
I havn''t had any luck with these 2 oxygen sensors.
after I clear the codes the light comes back within minutes.
I think Jesse is right, I'm going to have to OE.