Purchased a Bluetooth OBDLink MX+ scanner and it finally arrived today. I initially purchased it to help diagnose what I assumed (and confirmed) was a slow acceleration issue/low KCLV issue.

After playing with it for a bit, I finally checked to see if there were any codes and to my surprise, there was one - C1246 Master Cylinder Pressure Sensor

I don't have any CELs or other lights on at all. Brakes feel fine. I also couldn't find any codes with my regular ScanGauge II....

This looks like it should be the parts list for that area of things: https://www.lexuspartsnow.com/parts-...html?PNC=47202

Don't think this is directly related to the ISF...but it looks like good info: https://lexus-doc.ru/ileaf/lex99rm/l...bs/cic1246.pdf

I can't find much info online about this one for the ISF or really any ISX50 either...anyone have any insight or experience with this particular code?

 

No one here has reported this DTC before. The service manual says this:



There is a brake light switch and a pedal pressure switch on the brake pedal. The first thing to check is the brake lights. If they are not coming on, the brake light switch is likely the root cause. Bear in mind, the brake light switch is supposed to come on before the pedal pressure switch does. There is a test for this with Techstream. If this does not happen correctly, this code will be set. If it isn't this, then it's wiring or the skid control ECU.

 

Thank you very much. Awesome response. Will take a look. Any idea why the CEL didn't come on for this code?