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P2196 Code (Primary o2 Sensor)

kyoo

Ready to race!
All,

Car is a stg2+, which I've had to de-tune so that I can get emissions done - I tried once and they said they could not connect to the ECU on my car (MO).

I've put the OEM tune on the car, and I'm pulling a code - I half expected the rear o2 sensor code, but this is the primary o2 sensor? I was looking up reasons why the P2196 would trigger, but I'm unsure why it's happening. Cleared the code and came back. Could it be the aftermarket fuel pump? Or just a bad sensor?
 

BudgetPhoenix

Drag Race Newbie
Do you have an aftermarket downpipe on still? Are you by chance running it with a o2 spacer in an attempt keep the post cat o2 CEL off?
 

kyoo

Ready to race!
yes, and yes.

i thought i'd get the secondary o2 triggered, but this is the primary one

are you thinking it could be a differential thing? i.e., the secondary is too low compared to the primary, so the primary being triggered?
 
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BudgetPhoenix

Drag Race Newbie
yes, and yes.

i thought i'd get the secondary o2 triggered, but this is the primary one

are you thinking it could be a differential thing? i.e., the secondary is too low compared to the primary, so the primary being triggered?

Its probably the o2 spacer. These cars ECUs are very picky about spacers with a downpipe on the stock tune. The angle and spacing of the spacer can make a big difference. While the spacer is keeping your p0420 cat code off its still causing the p2196 because its detecting some gas mixture outside of normal parameters. I know the code shows its for the primary sensor but for some reason the spacer on the rear o2 can cause that code. Its happened to a lot of people including me. Some report only getting the code to turn off with certain o2 spacers namely the 42DD one which seems to work well. I had a generic one that did cause it to throw various rich/lean codes depending how far I spaced it and which angle i put it at when I tried running my stock file on my downpipe with the spacer installed. You can probably test if this is your issue if you remove the rear o2 spacer in your downpipe and then clear the codes and drive around. I bet the P2196 will go away but youll get the P0420 back. You can also just try throwing on your stock downpipe too.
 

kyoo

Ready to race!
Its probably the o2 spacer. These cars ECUs are very picky about spacers with a downpipe on the stock tune. The angle and spacing of the spacer can make a big difference. While the spacer is keeping your p0420 cat code off its still causing the p2196 because its detecting some gas mixture outside of normal parameters. I know the code shows its for the primary sensor but for some reason the spacer on the rear o2 can cause that code. Its happened to a lot of people including me. Some report only getting the code to turn off with certain o2 spacers namely the 42DD one which seems to work well. I had a generic one that did cause it to throw various rich/lean codes depending how far I spaced it and which angle i put it at when I tried running my stock file on my downpipe with the spacer installed. You can probably test if this is your issue if you remove the rear o2 spacer in your downpipe and then clear the codes and drive around. I bet the P2196 will go away but youll get the P0420 back. You can also just try throwing on your stock downpipe too.
that is basically the o2 spacer i have, but yea i think that's what's very possibly happening then. I dont have the stock dp, i bougth this car used, but i believe the downpipe does have a cat (not just test pipe), so there's a chance i'm ok without the spacer as well, i hope. Otherwise, I hadn't really considered the angle of the spacer, I imagine that u want to get as much flow to the o2 sensor as possible with the spacer in that regard.
 

BudgetPhoenix

Drag Race Newbie
Yeah I'm not sure what the optimal placement is for the o2 spacer. Ive seen some where its facing towards the front of the car. I'd say its worth it to pull it off and see what happens though after clearing codes.
 

kyoo

Ready to race!
p2196 went away and p0420 popped up - exactly as u suggested. I better figure out how to readjust the spacer, lol

guestion is - forwards, or backwards.. need some fluid dynamic analysis here lol
 
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kyoo

Ready to race!
k i'l give that a shot, thanks

does your dp have a hfc btw? i think mine is a hfc, which may make it read extra low compared to a test pipe
 
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kyoo

Ready to race!
ok - set to face backwards now, fingers crossed. If this doesn't work and p2196 pops up, i think just a short spacer will work to hit the right balance lol

IMG_20200319_200518.jpg
 

kyoo

Ready to race!
unfortunately the p2196 came back, even with the spacer repositioned. what may work better to get more flow is just a straight spacer (as opposed to angled one). kind of tricky, need the right amount of fumes to enter the sensor lol
 

JW with a VW

Go Kart Newbie
unfortunately the p2196 came back, even with the spacer repositioned. what may work better to get more flow is just a straight spacer (as opposed to angled one). kind of tricky, need the right amount of fumes to enter the sensor lol
Well...crap. Maybe replace the O2 sensor?
 

kyoo

Ready to race!
Well...crap. Maybe replace the O2 sensor?
to be clear - p0420 went away, and the p2196 came back - so it's definitely that i need to find the right amount of fumes to get to the rear o2 sensor.

what i'm trying next is a straight o2 spacer. this one is about the length of the "head" of the angled one, but no turn and no neckdown inside, just a straight tube.

if i still get p2196 with this one, then i need to get a shorter spacer

if i still get p0420 with this one, then i'm basically SOL and need to reinstall the oem downpipe.

hopefully, a straight spacer just gives it the right amount of fumes so that it just works.
 
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