Changed O2 sensors in response to P0135 code still having yellow emission code on OBDll unit.

Question

Followed the information that Reynaldo gave me and found O2 sensor in question to original problem was black at the base. The other two sensors looked normal with tan oxidation, but replaced all three O2 sensors since the vehicle has 95000 miles and the sensors were not that expensive. Reset the codes drove about 10 miles and now I am still getting a yellow caution code on emissions. No code is setting after driving another 20 miles. What I am seeing on the recorded live read out is a constant reading of 99 on the short term fuel trim (B1-S2) vs -7 to +7 on STFT on (B2S1) and (B1S1). What would cause this problem?

Answer 1

P0135 - 02 heater circuit malfunction bank 1 sensor 1

You are dumping fuel, some how, What is the short and long trim on bank 1, A reading of 99 on the short trim?Pull a sparkplug on bank 1 (this is where cylinder number 1 is located at) If any are black, you will need to go into more diagnosis, What can cause this is a injector leaking, You will need to narrow this down to a cylinder.

Answer 2

Short and long trim were -5 to + 7 vs -3 to 0 (primarily -2 to -3) on Bank 1. While the short term vs long term on Bank 2 was -13

 to 0 vs -1 to 0. The output voltage on all three sensors is 0, and the OBDII O2 sensor tests indicate that the values were all normal.