Poor fuel economy: Codes, Causes & Fixes

P0420 Powertrain The bank 1 catalytic converter no longer stores enough oxygen to clean the exhaust properly. 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 P0135 Powertrain The heater inside the upstream oxygen sensor on bank 1 isn't working or its circuit is faulty. Low P0172 Powertrain The engine computer is pulling as much fuel as it's allowed on bank 1 and the mixture is still… Moderate P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High

P0010 Powertrain The PCM found an electrical fault in the intake cam phaser solenoid circuit on bank 1, not… 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 P0013 Powertrain Electrical fault in the bank 1 exhaust cam phaser solenoid circuit; the exhaust cam stays… Low 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 P0020 Powertrain Electrical fault in the bank 2 intake cam solenoid circuit on a V or boxer engine; bank 2… Low 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 P0030 Powertrain The engine computer found a fault in the heater circuit of the upstream air-fuel sensor on bank… Low P0031 Powertrain The upstream sensor heater on bank 1 draws little or no current – usually an open heater… Low P0032 Powertrain The bank 1 upstream heater circuit looks shorted to power or is drawing far too much current. Low P0050 Powertrain The heater circuit of the upstream sensor on bank 2 – the side without cylinder 1 – is out… Low P0051 Powertrain The bank 2 upstream sensor heater draws no current: open element, lost feed or broken wire. Low P0069 Powertrain With the engine stopped, the manifold pressure and barometric pressure readings don't agree. Low P0075 Powertrain The intake cam timing solenoid on bank 1 has an open, short or bad driver circuit, so cam… Low P0088 Powertrain Rail pressure is running well above the value the engine computer is commanding. Moderate P0101 Powertrain The MAF sensor's airflow reading doesn't match what the engine computer expects… Low P0103 Powertrain The MAF claims more airflow than the engine could possibly take in, usually from a short… Low P0106 Powertrain The MAP sensor works electrically, but its pressure reading doesn't fit what the engine… Low P0108 Powertrain The MAP signal is pinned near 5 volts, so the PCM sees impossibly high manifold pressure even… Moderate P0110 Powertrain The PCM can't get a stable, believable signal from the intake air temperature sensor circuit. Low P0111 Powertrain The IAT reading is electrically fine but doesn't match the other temperatures the ECU knows. Minor P0113 Powertrain The intake air temperature signal is stuck at maximum voltage, which usually means an open… Low P0115 Powertrain The ECU can't get a usable coolant temperature signal; the sensor circuit is open, shorted… Low P0116 Powertrain The coolant temperature signal is electrically fine but doesn't behave the way the PCM expects. Low P0118 Powertrain The coolant sensor signal sits near 5 volts, so the PCM thinks the engine is frozen solid… Low P0125 Powertrain The engine stayed too cold for too long to switch to closed-loop fueling based on the oxygen… Low P0126 Powertrain The engine didn't reach, or couldn't hold, the coolant temperature the ECU needs for stable… Low