Codes P0174 and P0171

Hi Elccal,

More than likely you have a fuel issue however, here is a list of items that need to be run through starting with unmetered air entering the engine. This means air enters the engine after the MAF sensor. When this happens the PCM basically does not know that there is more air coming in because the MAF sensor tells the PCM how much air is entering the engine. When more comes in past the sensor, it leans out the air/fuel mixture which will cause hard starting and this DTC.

Here is a really good guide that will help explain this in more detail. Also, most of the items on the list attached that will cause this code are pretty easy to check. Even though they are unlikely the cause, they still need to be checked.

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers

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

https://www.2carpros.com/articles/evap-system-code-repair

Let me know what you find after you go through most of this but my bet based on the hard starting is a fuel issue or an air leak. Thanks

Hello and welcome to 2CarPros. Running lean on both banks is commonly caused by either a vacuum leak or by low fuel pressure or something like a MAF sensor that is contaminated or faulty.
The easy way to test for a vacuum leak is to start with a cold engine. Get a can of carb cleaner or engine starting spray. Start the engine and spray in short spurts around the intake manifold and lines. If you hear the engine suddenly change spray that spot again.
To check the MAF you simply remove it and use some MAF cleaner to remove any oil or contaminants like bugs or ?? from it. Reinstall and see if it is better.