Control module software needs to be updated, Vacuum leaks (intake manifold gaskets, vacuum hoses, PCV hoses, etc.), Mass air flow sensor, Plugged fuel filter or weak fuel pump, Plugged or dirty fuel injectors

Worn out spark plugs, ignition wires, coil(s), distributor cap and rotor (when applicable), Incorrect ignition timing, Vacuum leak(s), Low or weak fuel pressure, Improperly functioning EGR system, Defective Mass Air Flow Sensor, Defective Crankshaft and or Camshaft Sensor, Defective Throttle Position Sensor, Mechanical engine problems (i.e.—low compression, leaking head gasket(s), or valve problems)

Defective Engine Thermostat, Defective Engine Coolant Temperature Sensor, Defective Intake Air Temperature Sensor, Defective Cooling System, Low Engine Coolant, Dirty Engine Coolant causing incorrect Coolant Temperature Sensor readings, Defective/always running Engine Cooling fan(s)

Defective Intake Air Temperature Sensor, Dirty air filter, Defective Mass Air Flow Sensor, Faulty or corroded Intake Air Temperature Sensor wiring or connections

PCM software needs to be updated, Vacuum leaks (Intake Manifold Gaskets, vacuum hoses, PCV hoses, etc.), Faulty Mass Airflow (MAF) Sensor, Plugged Fuel Filter or weak Fuel Pump, Plugged or dirty Fuel Injectors

Camshaft variable timing solenoid failure, Engine oil level is too low, The engine is not timed correctly, The engine oil does not meet the manufacturer's requirements, Variable valve timing actuator failure, Worn timing chain

Camshaft variable timing solenoid failure, Engine oil level is too low, The engine is not timed correctly, The engine oil does not meet the manufacturer's requirements, Variable valve timing actuator failure, Worn timing chain

Worn out spark plugs, ignition wires, coil(s), distributor cap and rotor (when applicable), Incorrect ignition timing, Vacuum leak(s), Low or weak fuel pressure, Improperly functioning EGR system, Defective Mass Air Flow Sensor, Defective Crankshaft and or Camshaft Sensor, Defective Throttle Position Sensor, Mechanical engine problems (i.e.—low compression, leaking head gasket(s), or valve problems)

Worn out spark plugs, ignition wires, coil(s), distributor cap and rotor (when applicable), Incorrect ignition timing, Vacuum leak(s), Low or weak fuel pressure, Improperly functioning EGR system, Defective Mass Air Flow Sensor, Defective Crankshaft and or Camshaft Sensor, Defective Throttle Position Sensor, Mechanical engine problems (i.e.—low compression, leaking head gasket(s), or valve problems)

Worn out spark plugs, ignition wires, coil(s), distributor cap and rotor (when applicable), Incorrect ignition timing, Vacuum leak(s), Low or weak fuel pressure, Improperly functioning EGR system, Defective Mass Air Flow Sensor, Defective Crankshaft and or Camshaft Sensor, Defective Throttle Position Sensor, Mechanical engine problems (i.e.—low compression, leaking head gasket(s), or valve problems)

Worn out spark plugs, ignition wires, coil(s), distributor cap and rotor (when applicable), Incorrect ignition timing, Vacuum leak(s), Low or weak fuel pressure, Improperly functioning EGR system, Defective Mass Air Flow Sensor, Defective Crankshaft and or Camshaft Sensor, Defective Throttle Position Sensor, Mechanical engine problems (i.e.—low compression, leaking head gasket(s), or valve problems)

System too Rich (Bank 1)

Large vacuum leaks, Split Intake Air Boot or PCV Hose, Defective intake manifold gaskets, Mass Airflow Sensor (MAF), Mass Air Flow Sensor circuit and or wiring problems, Defective Barometric Pressure Sensor, Dirty or contaminated Mass Air Flow Sensing wire or filament, PCM software needs to be updated

Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor A)

Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor B)

Turbocharger/Supercharger "A" Underboost Condition

Camshaft Position Sensor A Circuit Bank 1 or Single Sensor

The Mass Airflow Sensor (MAF) Sensor is unplugged or the wiring is damaged, Loose or corroded electrical terminals in the MAF Sensor circuit, Faulty MAF Sensor

Crankshaft Position Sensor A Circuit Malfunction

Defective Oxygen Sensor/Air Fuel Ratio Sensor, defective Oxygen Sensor/Air Fuel Ratio Sensor Heater Circuit, Exhaust System Leak, Intake Air System leak, Low Fuel Pressure, Defective Engine Coolant Temperature Sensor, Defective sensor wiring and or circuit problem, PCM software needs to be updated, Defective PCM