Originally Posted by blackoutt

The p0420 and p0430 are 100% expected with upper catalyst removal and nothing to modify the O2 sensor signal but seems like you've already got that figured out. The only reason they logged after a drive is because you need to get up to certain conditions for that drive monitor to complete it's cycle. Spacers may or may not work to prevent these fault codes.

P0037 B1-S2 HEATER ISSUES O2
P0057 B2-S2 HEATER ISSUES O2

These are most likely related to either plugging in the sensors connector not fully seated, damaged wires, or bad sensors. If it's a damaged common ground to the heater on one of the O2 sensors it could cause the other sensor fault to log too without being bad at all. I would carefully do continuity and pin to pin short checks in the sensor harnesses and from the sensors connector to ECM connector. You have the right part number sensor and the ones I ordered from amazon recently looked exactly like the stock sensors so they shouldn't be longer? You can measure the heater circuit of the sensors to see if there is any resistance like a heater should have, or an open or a short indicating a bad sensor.


P0102 MAS AIR FLOW SENSOR

1440& 1443 0AIR INJECTION SYSTEM

These are all related to your slyfox bypass, check the wire spliced into the MAF plug, I had mine come unhooked once and cause a 102 but I didn't log 1440 and 1443 because somehow my AIP and valve is still operational! These faults can cause limp mode. Fix this first then go back to the O2 sensor issue separately.


My personal saga with a similar setup is that with 3 stacked spacers I still got a P0430 after I installed the DT ypipe. I ended up going with a URD O2 simulator and recently posted a thread about issues with install but we figured it out (tan wire must be wired to GROUND not signal reference). The signal simulator eliminates the need to spacer O2 sensors in the ypipe making it a less tight fit between sensor and the bottom of the body. The O2 sensor wire on the passenger side still needed to be unclipped from the first holder to be long enough.

EDIT: I don't think DT knows much about the exact application, they told another member to put spacers on the UPSTREAM air/fuel ratio sensors. So I wouldn't listen to them. I'm sure they have a good general knowledge of this stuff but spacer on the upstream would cause poor running issues. Only ever put spacers on the y pipe sensors.