A couple days ago my CEL illuminated and the VSC is intermittent as we know is an issue with this year of Lexus. I got the codes from a dealership and they came back P0125 and P1155 and recommended to replace the front two sensors. I have tried the gas cap, fill the tank, check hoses but I am reluctant to replace two sensors at once as it seems to be a chain reaction.

Any thoughts? Which of the two sensors would you replace first to see if that helps?

Thanks all

 

At this point none of them. This is one of the reasons I bought my own scanner to look at the A/F sensor readings before going on expensive 'fishing expeditions". However, if even after the code has been reset (and this being after you've filled up the gas tank at least) and the readings on the A/F sensors are not line with specifications, the A/F sensor visible on the front exhaust manifold is what would likely be the one needing fixing at that point.

 

Thanks for quick reply. Which bank sensor combo number are you suggesting?

 

You'd have to get someone with a more advanced OBD2 scanner that can read A/F sensor readings. Generally they should hover around .650/.660 or so in idle.