Code P0172 comes on and off periodically by itself?

JJDKSK

MEMBER
2015 AUDI A7
3.0L
V6
TURBO
4WD
AUTOMATIC
125,000 MILES

Code p0172 comes on and off periodically by itself. The car runs great but on some hot days after driving once then turning on later the car would crank and sometimes not start until I try again. After starting it can have a rough idle but will go away and the car will drive fine again. Doesn’t have any loss of power, good MPG and sounds normal. The code goes away on its own and shops can’t figure it out once it’s gone, what could this be?

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

This can be caused by a few different things, Weak MAP sensor, intake runner control not opening fully, a weak high pressure pump or a partially clogged catalytic converter.

Here is a guide to help you check the cat:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Here is a guide that will help explain the causes of rich exhaust.

https://www.2carpros.com/articles/why-an-automotive-engine-will-run-rich

The P0172 code on a 2015 Audi A7 3.0L indicates that the engine control module (ECM) has detected that the air-fuel mixture is too rich in Bank 1.

Here are the locations of the MAP sensor and the cat for bank 1. You should be able to go to live data on the scanner and see the reading from bank 1 and bank 2 which should so differences which can help us as well. Check out the images (below). Please upload pictures or videos in your response of any problems so we can see what to help you with.

Images (Click to make bigger)

Code P0172 comes on and off periodically by itself?

1 Reply

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