P219A – Bank 1 Air-Fuel Ratio Imbalance
Here is what I found searching it on two other sites:
From SVT Performance:
1) Mismatched 02 readings (I am paraphrasing). It seems to be a side effect of going catless. Some say that you have to have a leak to trigger this code, but I have none. I clear this code out several times a week. It is getting annoying.
2) Yes, if the intake is leaking on one side, it will cause your short terms to be different from side to side, and you would see that.
3) This happened as soon as I installed the cat delete pipes.
4) some tuners elect to turn down the sensitivity in this area to prevent the codes.
5) I've been getting the same issue on E85, and now and then on gas as well.
I've found on stock vehicles that the DTC is generated by excessive oscillation in the O2S11_CUR (and 21) pids which more often than not is an injector issue.
6) Im thinking the combination of variable cam timing and scavenging(SP) of the long tube headders has something to do with this code.
7) Turned this code off permanently the last time I got a tune revision. Good riddance.
1) 2012 5.0 Manual 6 speed Off Road X pipe, Ghost Cam tune, Muffler delete, Steeda CAI. Just threw a CEL pulled over immediately grabbed tuner and got the code "P219A"
2) I would check all vacuum and exhaust connections, just to make sure they are tight.
most likely you have a small exhaust leak that is causing it
3) It's the rear 02 sensors that cause that to throw that code. I had my shop add extenders and have not had a problem since.