Check engine light on, OBD2 codes: P0171 and P0174

Good morning,

The codes have many possibilities but the most common is low fuel pressure. It needs to be checked to verify enough fuel is being sent to the engine.

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

A mass air flow is another possibility as well.

https://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf

You will need special tools for these checks. A scan tool that can read live data and a fuel pressure tested.

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

Roy

Hello there. Just wanted to jump in here. Inspect the air boots on the air cleaner to throttle for leaks. If good then look at the data list if your scan tool can look at that. Mass air flow data at idle with engine warm and all accessories off should read close to engine size.

If all is good then cruise with a co pilot. When at 40MPH hit the accelerator pedal to the floor. The mass air flow sensor reading should rise close to 100 grams per second. The higher the better. If you do not hit the target then the mass air flow sensor is bad.

Majority of the time the mass air flow sensor is the culprit and I strongly recommend a dealer part over after market in this scenario. After market mass air flow sensors are hit and miss and are usually not calibrated properly. Do the test mentioned and let us know the readings please if you need further assistance.