My Check Engine light is on with codes P0171 and P0174. I believe the problem is being caused by an intake leak. If it turns out that is not the problem, I have a few other ideas on what can be done to fix it, namely replace the air filter and the front oxygen sensor, and clean the air flow meter.
Codes P0171 and P0174 are lean codes for bank 1 and bank 2 (both sides of the engine). Dozens of problems can cause these codes to set, from a vacuum leak to a clogged fuel injector. While the mass airflow sensor and intake leak could be the problem, you can rule out the air filter. The O2 sensor is also unlikely since you have codes for both banks and it would be unusual for both the upstream O2 sensors to be bad. A trained technician, such as one from YourMechanic, will be able to diagnose and repair your Hyundai.
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