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

P1128 Volkswagen · Powertrain VW's part-load fuel adaptation has maxed out adding fuel on bank 1 – the engine runs lean as… Moderate P1129 Jeep · Powertrain The PCM couldn't switch bank 2 of your Jeep's V6 or V8 into oxygen-sensor-controlled fueling… Low P1132 Ford · Powertrain Ford's front O2 sensor on bank 1 keeps reading rich even though the PCM has pulled out as much… Low P1133 Chevrolet · Powertrain The front oxygen sensor on bank 1 isn't flipping between rich and lean often enough during GM's… Low P1134 Chevrolet · Powertrain Bank 1's front O2 sensor reacts much faster in one direction (rich or lean) than the other. Low P1135 Toyota · Powertrain The heater inside Toyota's upstream air/fuel ratio sensor is drawing too much or too little… Low P1137 Volkswagen · Powertrain At idle the VW computer is pulling out as much fuel as it's allowed on bank 1 and the mix… Low P1152 Ford · Powertrain On a Ford V6 or V8, the bank 2 front O2 sensor sticks on rich even after the PCM leaned that… Low P1153 Chevrolet · Powertrain The front O2 sensor on the passenger-side bank of a Chevy V6/V8 isn't cycling rich-lean often… Low P1154 Chevrolet · Powertrain On a Chevy V6/V8, the bank 2 front O2 sensor rises and falls at clearly different speeds. Low P1155 Toyota · Powertrain The heater in the front-bank air/fuel ratio sensor of a Toyota V6 or V8 is out of its current… Low P1157 Honda · Powertrain The signal lines of Honda's upstream air/fuel ratio sensor read too high, usually an open… Low P1166 Honda · Powertrain The circuit that powers the heater in Honda's upstream A/F sensor is open, shorted or unpowered. Low P1167 Honda · Powertrain The upstream A/F sensor heater is powered but isn't drawing the current or heating the sensor… Low P1272 Nissan · Powertrain The front air/fuel ratio sensor on bank 1 isn't sending a usable, moving signal to the Nissan… Moderate P1273 Nissan · Powertrain Nissan's ECM sees the front air/fuel ratio sensor on bank 1 reading lean for too long and flags… Low P1281 Jeep · Powertrain Your Jeep's engine didn't reach operating temperature in time, most often due to a stuck-open… Low P1289 Ford · Powertrain The CHT sensor signal on your Ford is stuck near 5 volts, which the PCM reads as an impossibly… Moderate P1296 Volkswagen · Powertrain The VW ECU saw coolant temperature behave differently from its model – usually a sensor… Low P1346 Toyota · Powertrain Toyota's ECM sees the intake cam signal in the wrong place relative to the crankshaft signal. Moderate P1349 Toyota · Powertrain Toyota's VVT-i system isn't moving the intake camshaft to the position the ECM is asking for. Moderate P1354 Toyota · Powertrain On a Toyota V6 or V8, the bank 2 intake camshaft isn't reaching the timing the ECM commands. Moderate P1656 Toyota · Powertrain Toyota's ECM has found an open or short in the electrical circuit of the VVT-i oil control… Low P2002 Powertrain The ECU thinks the diesel particulate filter isn't trapping soot properly — or it can't measure… Moderate P200A Powertrain The ECU switched the intake runner flaps but the system didn't respond the way it should. Low P2096 Powertrain The sensor behind the catalytic converter keeps reporting lean, and the ECU has run out of room… Low P2097 Powertrain The sensor behind the converter keeps seeing rich exhaust, and the ECU can't lean the mixture… Low P2177 Powertrain Bank 1 goes lean once the engine is above idle, so the PCM keeps adding fuel at cruise… Moderate P2178 Powertrain Above idle, bank 1 carries more fuel than the PCM asked for, and pulling fuel out no longer… Moderate P2181 Powertrain The engine isn't warming up or holding temperature the way the computer's model says it should. Low