ual320jet

I have read the other posts on this issue. I have a 2002 with 51000 miles. The other day the light came on and I went to Auto Zone to check for the code. Bad O2 bank 2 sensor 1. I changed it out, very hard to get to. Disconnected battery for 10 minutes to clear code. Light came back after some driving, went to Auto Zone, now I have codes: P0125, P0430, P0155! The car starts fine and runs fine. Gas mileage is good. I am going out of town for three days before I can get back to this and would like your input or similar experiences. I think the plug on th O2 sensor might not be tight, causing all these codes, since it was very diffucult to get to. Gas cap was tight and I swapped it with my LS430, they look the same. Tank is full, engine temp in the middle. Thank you CL members for your help! I will take any advice.

UnSub

I don't have a list of what the codes mean but am curious what brand sensor you bought. Many people on the Tundra Solutions forum report problems with brands other than those that come in our Toyota's. I think they are Denso brand but perhaps someone else can comment.

ual320jet

I put in an NKG. But their O2 sensors are called NTK part #24564

VVTiBob

The 125 error code deals with the exhaust temperature but involves sensors 1 on both banks.

The 155 error points to a malfunction in bank 2, sensor 1

The 430 error also points to bank 2, and deals with the waveform before and after the Catalyst in amplitude. In other words it compares what's going on between sensor 1 and sensor 2 after passing through the catalyst.

So three error codes are pointing to sensor 1 on bank 2.

But the 125 error also points to a few other issues: Air induction, low or no fuel or issues with fuel pressure, high or low, a damaged PCV hose connection, gas leakage on the exhaust or problems with the Engine Control Module or ECM.

To sort it all out you'll need to hook up a scan tool and take some voltage reading from the sensors.

Pearlpower

iTrader: (2)

When you say you changed it out, did you splice one in, or actually changed out the entire unit? Splicing can cause some serious issues with O2 sensors which is why I ask. As I do not believe in coincidences, I would focus on the first issue first before moving on.
Get back under there and retrace your steps as sometimes we can cause other issues by mistake while repairing something. Just my .02. Good luck.

ual320jet

Thank you for all the input! It ended up the O2 sensor was just loose. It was hard to get my big hands it the small space. After I heard the click, I knew the problem was solved! No Check Engine Light!!!