Post Piggies - O2 Codes

B6/7 S4/RS4
#1

Post piggie installation (top CAT material cleared, lower CAT left in place) and I’m throwing codes on the passenger side (both front and rear). Drivers side is not throwing any codes. I have “L” shaped O2 spacers on the lower sensors on both sides. Codes have been cleared a few times to make sure they were not temporary. Codes / Check Engine light come on after a while.

Codes
Passenger Side, Upper/Front - sensor part# 1K0998262AA
P2196 O2 Sensor Signal Biased / Stuck Rich (Bank 1, Sensor 1)

Passenger side, Lower/Rear - sensor part# 022906262BM
P0138 O2 Sensor Circuit High Voltage (Bank 1, Sensor 2)
P0141 O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2)
P0036 Heated Oxygen Sensor (HO2S) Heater Control Circuit (Bank 1, Sensor 2)
P0139 O2 Sensor Circuit Slow Response (Bank 1, Sensor 2)

I had a somewhat reputable VW/Audi place perform the work, but not sure I trust them 100%… I know it is somewhat common for the sensors to need replacing after doing piggies (broken wires, damaged sensor, change in exhaust flow from norm). The only work performed at the time was piggies.

So, what I’m wondering: I’ve read where the sensors were swapped, which causes problem - not sure if that is a possibility here with these codes. I’m getting ready to order replacement sensors - but I’m confused on the Bank 1, sensor 1 code outside of a damaged sensor. any thoughts?

#2

Well the rear 02 is done and needs replacement from what the codes say.

The front is possibly damaged but I would first replace the rear 02 and see if that helps the front sensor read better. The sensors work together so that can cause issues. The L or 02 spacers dont help the car run optiomal getting the JHM tune and pulling out the L 02 spacers might be a good bet. Still the rear 02 is going to need to be replaced.

#3

Thanks! I appreciate the quick and solid advice this forum continually gives.

I’ve ordered a replacement sensor for bank 1, sensor 2. we’ll see how the replacement goes.

#4

they tend to go while taking the downpipes out. some say if it gets knocked around the O2 will just fail. might have been what happened.

#5

yeah, that is what I’m assuming happened. Now the fun part - trying to get your hands/arms twisted in the right position to actually remove the damn things…

#6

on the rs4 the connectors can be hard to get to. One of the best ways to stop there from being damage on removal issues is to unplug the connector from the body side wire harness first. That way the end of the connector can spin free and the wires dont get stretched.