4th Generation – 2014 Subaru Outback Runs Poor and Warning Indicators Come On When Temperatures Are Below 0F

Are you monitoring long term and short term fuel trim via OBD to know what is really going on? It is a feedback system and uses the front A/F sensor to monitor and adjust the mixture. Have you read the codes or examined the waveforms to help pinpoint what is going wrong? Does the intake temperature sensor track ambient temperature?

I’m not sure what “known problem” means either, but there are plenty of diagnostic tools at your disposal to help determine whatever problem your car is having.

How do you know it’s “working lean”?
Exactly what A/F ratio are you talking about?
How did you measure the A/F ratio?

I have never heard of this before… Where do you base this statement??

A person experienced with OBDII code readers should be able to isolate the issue. Need to monitor/graph relevant live data like (MAF, Intake Air Temp, Front O2 Sensor, STFT, LTFT…etc)

Good morning.
The first time this problem occurred was on 2/16/2021 when the outside temperature was -25F. I had the car towed to my mechanic and they found the following codes:
Engine: P0171 – System too weak
ABS: C0057 – VDC was interrupted for engine reasons
Of the page
B2806, B2807, P00A8, P07A8, P0600, P0002, B2807, B2806, P0300
They reset all the codes and while the car warmed up inside their garage there were no other issues the car ran fine.
The second time this problem occurred was on 12/22/2012 when the outside temperature was -10F. I continued to drive the car because it was running fine. When I got home I used a handheld OBD device and found the following codes:
Engine: P0171 – System too weak
ABS: C0057
P0420, P0171
I cleared all the codes and haven’t had any problems since. The engine was and continues to run well.
My mechanic suggested that this issue could be related to the use of a plastic intake manifold?