Poor fuel economy: Codes, Causes & Fixes

P0135 Powertrain The heater inside the upstream oxygen sensor on bank 1 isn't working or its circuit is faulty. Low P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High P0420 Powertrain The bank 1 catalytic converter no longer stores enough oxygen to clean the exhaust properly. Low P0430 Powertrain The bank 2 converter on a V6, V8 or split-exhaust engine isn't cleaning the exhaust well enough. Low P0101 Powertrain The MAF sensor's airflow reading doesn't match what the engine computer expects… Low P0113 Powertrain The intake air temperature signal is stuck at maximum voltage, which usually means an open… Low

P0011 Powertrain The bank 1 intake cam sits further advanced than the PCM asked for, usually an oil or control… Moderate P0012 Powertrain The bank 1 intake cam lags behind the angle the PCM wants, often from chain stretch or weak oil… Moderate P0014 Powertrain The bank 1 exhaust cam won't follow its target and stays too far advanced; think oil, valve… Moderate P0015 Powertrain The bank 1 exhaust cam sits later than commanded; a stretched chain or stuck exhaust phaser… Moderate P0017 Powertrain The bank 1 exhaust cam signal doesn't line up with the crankshaft; think chain, exhaust phaser… Moderate P0022 Powertrain The bank 2 intake cam can't advance as far as the PCM asks; phaser, oil pressure or a worn bank… Moderate P0024 Powertrain The bank 2 exhaust cam stays too far advanced or reacts too slowly; check the valve, the oil… Moderate P0088 Powertrain Rail pressure is running well above the value the engine computer is commanding. Moderate P0108 Powertrain The MAP signal is pinned near 5 volts, so the PCM sees impossibly high manifold pressure even… Moderate P0132 Powertrain The upstream oxygen sensor on bank 1 reads too high: the engine is running rich or the signal… Moderate P0170 Powertrain Bank 1 fuel correction is far outside its normal window, lean or rich, and the ECU won't say… Moderate P0172 Powertrain The engine computer is pulling as much fuel as it's allowed on bank 1 and the mixture is still… Moderate P0173 Powertrain Fuel correction on bank 2, the side without cylinder 1, is out of range or unstable, lean… Moderate P0175 Powertrain Bank 2 is still running rich even though the PCM is already cutting fuel on that side as far as… Moderate P0206 Powertrain Injector 6's circuit is open or faulty. On an inline-six that's the rear cylinder, tucked under… Moderate P0208 Powertrain The circuit to injector 8, the rear cylinder on bank 2 of a V8, is open or doesn't respond… Moderate P0266 Powertrain The engine computer can't even out cylinder 2 with fuel corrections; its balance rate is past… Moderate P0272 Powertrain The ECU can't balance cylinder 4 against the rest anymore; its fuel correction is outside… Moderate P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High P0303 Powertrain Cylinder 3 is misfiring. Check whether it misses at idle or under load before you blame… Moderate P0341 Powertrain The bank 1 cam signal lands at the wrong crank angle, often from a stretched chain or a sticky… Moderate P0346 Powertrain Bank 2's cam signal arrives out of position. On V6/V8s that often means a bank 2 chain, guide… Moderate P0352 Powertrain Coil B, normally on cylinder 2, has a circuit fault. Where cylinder 2 sits depends… Moderate P0366 Powertrain Bank 1 exhaust cam signal is out of position: chain stretch, a sticky exhaust phaser… Moderate P052E Powertrain The crankcase ventilation regulator isn't controlling crankcase pressure properly – often… Moderate P0734 Powertrain Fourth gear (overdrive on four-speed units) doesn't hold the expected input-to-output speed… Moderate P0735 Powertrain Fifth gear slips or isn't fully applied; the TCM measures a ratio that doesn't fit 5th. Moderate P0741 Powertrain The torque converter lockup clutch slips or won't engage when the computer commands it. Moderate P0744 Powertrain Lockup control drops in and out: an intermittent TCC circuit, or on some makes a lockup… Moderate P0755 Powertrain The TCM detects an electrical problem with shift solenoid B, the second on/off shift valve. Moderate