P0156, 0158

I am getting a bank 2 sensor 2 CEL. I replaced the sensor behind the cat and cleared the code only for it to return after a short drive. I swapped the 2 #2 sensors to see if the problem would move to the #1 side but the problem remained on the #2 side. Looking at the voltages of the 2 sensors while driving, both operate normally for about 10 minutes, then the #2 sensor goes to 3V and stops moving. Any ideas what might be the problem?

 

Need more info. Vehicle year and which engine, V6 or V8.

 

2006 2uz-fe(v8)

 

You say you replace both O2 sensors (after the cats) and are still getting the codes? What brand O2 sensors did you use? How many miles are on the truck?

 

Denso, 225k. The service manual troubleshooting guide indicates that it's the air/fuel sensor or the ECM. I don't have the toyota tester unfortunately and my obd2 reader doesn't have all the info the service manual calls for.

 

When you do a cold start, do you hear ticking from the exhaust? 200K miles and you exhaust manifolds might be cracked and ready for replacement. Mine were and I was getting recurring CELs like yours, even with new O2 sensors. Replaced both manifolds (the cats are part of them) and new exhaust gaskets and all my O2 related codes were gone and haven't come back. It's very possible that you have cracked exhaust manifolds that are letting extra air into the system and causing the codes.

ECM on these are extremely rare to fail.

 

I haven't heard any new sounds from around the manifolds, I will take another look though.

 

I would hear the tick sound on a cold start and then putting it into gear to pull out of the garage. Very noticeable. I'm not saying that is your issue but it's a possibility. Exhaust manifolds on the V8 at this mileage is fairly common. It's just unfortunate the cats are part of the manifolds which makes them more expensive. Highly recommend stock if you were to replace them. The cats in the less expensive aftermarket manifolds are known to fail, even the high end stuff like Magnaflow.

 

Yeah that it what I gather from looking around the forums. Thanks for the heads up.