Autel Maxidas DS808 Short term fuel trim oscillates

Is the short term changing between 4 and 14 just sitting at idle in closed loop with the accessories off?

Could you please include the code definition for p0037? It just makes it easier for everyone reading.
Thanks Monde

The oscillation of the downstream sensor is what is causing the P0420. The downstream should be fairly steady, and slightly RICH.

I did some digging on Infinity's DTC setting criteria, and it looks like to throw a P0171 and P0174, you need to be in closed loop at cruising speed, and the ECU compares the reading to a previous benchmark from an old trip.

Link: Infinity DTC Criteria
I can't attest to the accuracy of that list, but it seems reasonable to me.

Did you have to fix anything? I'm curious what your Alpha was while this was happening, if you noticed?

In the sense that it is an immediate response. Since there isn't another trim, like long term to reset a baseline, I feel like it's more of just a total trim. Stoich is 100.If a car with a vacuum leak comes in, it will be like 120 but drop down closer to 100 with some RPM, liked you'd see with fuel trims.

I'm still used to using global obd2 fuel trims but am giving in to the enhanced data, since it's the make I work on daily.

So they do use something sort of like long term in a PID called self-learning. I think it's described as being used if the trimming is outside of the Alpha trim range. I think the highest Alpha is like 125, so it might have pegged out there and also show up under self-learning. I have just been looking at Alpha though, since it seems to give all the info you need on the current mixture.

No problem! I read about that information in the Nissan/Infiniti OBD2 training manual. I haven't gone to school for that class yet, so if I do and learn that I misunderstood any of that, I'll update the info here.

Yes, especially with so many cars using A/F sensors now up front. All of the Nissans use them, so I expect to get a lot of experience with them.