2009 Base R56

Throwing a P2414 Code. Torque OBDII app shows: O2S1Eq = 2,00, AFR = 29.38, Vacuum 23.30, O2S1C = 1.7mA, O2S2V is normal (.1 to .9)

When I pump the brakes the AFR goes down as do the other O2S1 Readings. When I remove the brake booster vacuum, the AFR goes down as do the other O2S1 Readings, then return to the high readings even with the vacuum disconnected.

The fact that the readings go down, seems like the sensor is working OK. I plan on pulling and cleaning the pre cat O2S1 sensor anyway.

Any ideas what's going on?

Thanks!!!

More info. Prior to this problem, I broke the serpentine belt. The car over heated but ran fine. I had to replace the thermostat. Doesn't sound like there is a cracked exhaust manifold.

Note re: Torque screen shot. The low values on the gauges indicate when I pumped the brakes or disconnected the vacuum hose. The car is not warmed up, but I get the same readings when it's warm.

 

Update. Removed the heat shield and checked the exhaust manifold. Don't see or hear any sign of leaks.

 

replaced O2 upstream sensor. Fixed the problem.