Code PO172

Hi,

By any chance, do you have access to a live data scanner? The code indicates bank 1 is running rich. It's a 4 cylinder so there is no bank 2. A rich mixture simply means there is too much fuel entering the combustion chamber and not enough air. The air/fuel ratio is off.

I need to know a couple of things. If you have a live data scanner, let me know what the short-term fuel trims are. Also, if you feel a misfire, there should be other codes. Is this the only one? Have you ever noticed black or gray smoke from the exhaust? Any odd smells?

The idea that they did the things you indicated leads me to believe that either you have a faulty fuel pressure regulator or there is a wiring issue between the o2 sensor and the ECM. Heck, it could be something as simple as a restriction in the air induction (air filter box and hose that goes to the throttle body).

Let me know if they replaced anything other than the injectors with the fuel system. Also, please confirm this is a 2.4L. You indicated a 4 cyl but typed 2.7L.

I'm including a couple of things I would like for you to check. See below.

If they haven't done anything with fuel pressure, here is a link that explains in general how it's done. You will need a fuel pressure gauge, but most parts stores will lend you one.

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

I attached a pic below showing possible causes for the code.

Pic 2 below shows the fuel pressure regulator. I highlighted a vacuum hose that runs to it. Remove that hose and check for evidence of gas in the vacuum hose. Also, have a helper start the engine and confirm there is vacuum to the hose.

Pic 3 is the manufacturer's specifications for fuel pressure.

Let me know as much as you can and what you find.

Take care,

Joe

See pic below.