Code P0172

LALMEN21

MEMBER
2009 CHEVROLET HHR
2.2L
4 CYL
2WD
AUTOMATIC
198,000 MILES

Got a system too rich bank 1 code. I changed the spark plugs and coil packs, changed the mass air flow sensor, changed MAP sensor, changed the 2 oxygen sensors, changed the fuel injectors, cleaned the throttle body. It still stutters and stalls out. I don't know how to perfectly do a vacuum leak test but I'm not even sure that's the problem, hence why I'm posting. Can you point me in the right direction?

Sunday, August 29th, 2021 AT 6:25 PM

1 Reply

JACOBANDNICKOLAS

MECHANIC
110,077 POSTS

Hi,

Based on that code, you are getting too much fuel to the engine. In this case, it wouldn't be a vacuum leak. A vacuum leak would allow unmetered air to enter the engine and create a lean mixture. This code can be caused by several things. However, here is a link that shows how to test for a vacuum leak:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Have you checked fuel pressure? Is this the only code present? If you have a live data scan tool, could you let me know the short-term fuel trims?

Make sure there are no restrictions in the air intake tube/air filter box. Also, check fuel pressure. Here is a link that shows how it's done:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

I attached the manufacturer's pressure specifications below. Do this and let me know what you find.

Take care,

Joe

See pic below.

Image (Click to make bigger)