Excessive Fuel Consumption

NOTE: Unless otherwise indicated, see appropriate SYSTEM & COMPONENT TESTING article for testing procedures.

Check idle speed and ignition timing adjustment. See IDLE SPEED, IGNITION TIMING & IDLE MIXTURE RATIO ADJUSTMENT in ON-VEHICLE ADJUSTMENTS article.
Check throttle position sensor adjustment.
Check battery and generator circuit. See appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS.
Check starter circuit and signal plate.
Check PNP switch.
Check injector circuit.
Check electric throttle control actuator.
Check ignition circuit.
Check camshaft position sensor circuit.
Check Mass Airflow (MAF) sensor circuit.
Check A/F sensor one.
Check Engine Coolant Temperature (ECT) sensor circuit.
Check heated oxygen sensor one circuit.
Check Throttle Position (TP) sensor circuit.
Check fuel pump circuit.
Check IACV-AAC valve circuit.
Check IACV-FICD valve circuit.
Check EGRC-solenoid valve circuit.
Check EGR system.
Check main power supply and ground circuits.
Check knock sensor circuit.
Check vehicle speed signal circuit.
Check ECM.
Check intake valve timing control solenoid valve circuit.
Check Park/Neutral Position (PNP) switch circuit.
Check air conditioner circuit.
Check fuel pressure regulator system.
Check EVAP system.
Check PCV system.
Check refrigerant pressure sensor circuit.
Check fuel piping and valve deposit.
Check fuel condition.
Check air duct and air cleaner.
Check for air leakage from air duct.
Check electric throttle control actuator.
Check for air leakage from intake manifold, collector and gasket.
Check cylinder head and gasket.
Check timing chain and camshaft.
Check intake valve timing control, intake valve and exhaust valve.
Check exhaust manifold, tube, muffler, and gasket.
Check three way catalyst.
Check oil pan, oil strainer, oil pump, oil filter, oil gallery, and oil cooler.
Check oil level and condition.
Check radiator, hose and filler cap.
Check thermostat, water pump and water gallery.
Check cooling fan.
Check coolant level and condition.
Check cylinder block, piston and piston ring.
Check connecting rod, bearing and crankshaft.
Check hydraulic lash adjuster.
Check cooling fan.