My mechanic is having difficulty diagnosing a P2190 code on my 2012 Express (4.3L V6). The van doesn't have any drivability issues other than on very very rare occasions I get a mildly surging idle. All 4 O2 sensors were recently replaced to cure an intermittent P2270 and what he said was some slow switching of the sensors. The P2190 popped up right after this work was done. He says that fuel trims look good which doesn't make sense to me because I thought an out of range fuel trim was what sets this code. He's returned the vehicle to me and said its safe to drive for now and he'll investigate further in a month or so when I can do without the van for a longer period of time. Any suggestions are welcome.

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Strangely I could not find the diagnostic parameters for P2190 in GM documentation for the LU3 engine (https://gsitlc.ext.gm.com/gmspo/mode6/). I found it under a different engine which says the error is et under low speed and low load when the bank 2 additive fuel load correction (i.e. I believe this means short term trim) is <-6.0%.

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Its a P219A. My old code reader was not reading it right. Unfortunately I can't edit the title of the thread.

 

What brand of O2 sensors? Made in China junk? Sometimes a fix isn't a fix because of the poor quality of the replacement part.

 

NGK. He said he was unable to get OEM.

 

NGK is a good brand in my book. Might have to look at the wiring next.

 

Turns out its a P219A - Bank 1 Air-Fuel Ratio Imbalance (not P2190). My old scanner was misreporting the code. I was suspicious of that when I couldn't locate any info on this code for the Lu3 engine. So now I'm digging into the freeze frame data attached.

 

So, its been a couple of weeks. Took the van to another independent mechanic for a second opinion. He provided pretty much the same non-diagnosis. Confirmed fuel trims were normal, confirmed no misfires, could not find any intake leaks, did upper intake cleaning (whatever that is), and dumped a can of injector cleaner into the tank. Didn't think the non-OEM O2 sensors were to blame but swapped the left and right upstream O2 sensors just to see if the DTC code would follow the sensor (it didn't). Its still P219A. Recommended I drive it for a few weeks and then he'd have another look at it. I asked him about clogged or leaky injectors and, like my regular mechanic, didn't want to go there just yet. Been doing lots of googling and it seems like Air/Fuel ratio imbalance is not very common in non-GDI engines and is notoriously hard to diagnose. Lot of problems posted and few solutions other than replacing injectors.

 

try the troubleshooting here

https://www.obd-codes.com/p219a

 

SOLVED! After spending a bunch more time investigating, my mechanic replaced the almost new NTK upstream O2 sensors with genuine GM ones and put in a new set of plugs and wires. The problem is now gone. Its been about 2 months and 2,000 kms. I'm a happy camper.