P0172 & Fuel rail pressure rises after engine off?


Passed Driver's Ed
As I am experiencing P0172 [system too rich] these few months, i have been looking at OBD trying to fix the problem.

I just noticed today that:
The hpfp stays at 40 bar at idle, but when I turns off the engine.
I saw the Fuel rail pressure rises till 58 bar.
Is it normal for this to happen?

And on some occasion, the car wont start unless I give it some gas.

Things I have did in the past few months:

New injectors
New intake manifold
New PCV and hoses
New Coil
New O2 sensor
Cleaned MAF sensor

Please help, the problem has been bothering me so much and I really hope to fix it. :(
Last edited:


New member
Hi, also having similar problems, did you ever manage to fix this issue with over fuelling causing carbon build up? Also changed a lot of parts.