p1135 and p0126 codes 2001 tacoma

I have a 2.7L I-4 5 speed manual 2001 Tacoma

It seems to be running and operating just fine excluding codes continuing to pop up. Temperature is regular and fuel use is average as well. I have continued to get a p1135 and p0126 code.

p1135 is the bank one sensor one O2 Sensor which I replaced without any issues.

P0126 is insignificant coolant temp. With temp running normal, I figured it might be the ECT Sensor. Purchased new sensor but was between engine wall and block and was unable to get at it.

Took into local shop and they ran a number of tests. Temp was good, ect senor was working properly and the new O2 sensor checked out too. Once clearing codes again, they took it out and the same codes came up.

They suggested it might be a vacuum issue somewhere which is throwing off the sensors. Without having a smoke machine they couldn't test for any sort of vacuum leak. Anyone experience or have thoughts as it is seems to be running fine but continuing to have check engine with P0126 and P1135?