Here are some of the most common P0172 causes. Dirty/broken mass air flow (MAF) sensor Vacuum leak Fuel delivery or pressure malfunction (High fuel pressure, bad fuel injector) Contaminated/ defective oxygen sensor Bad coolant temperature sensorI have a 2013 Tahoe that is throwing codes of P0172, 175 and check engine light. It has been tuned up, new throttle body, canister replaced, Map sensor O2 sensor, module by the gas tank programmed and changed and over a thousand dollars later, still the same problem! I am begging for help! Thank you.