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

P0760 Powertrain A fault in shift solenoid C's circuit – usually means lost overdrive or upper gears, or limp… Moderate P0A1F Powertrain The module that manages the high-voltage battery failed its self-check or reports implausible… Moderate P0A7E Powertrain The high-voltage battery got too hot. A clogged cooling intake or dirty fan is the usual cause. Moderate P0A7F Powertrain The battery computer has calculated that the whole high-voltage pack has worn past its usable… Moderate P0A80 Powertrain The hybrid system sees weak or unbalanced modules in the high-voltage battery and flags… Moderate P1128 Volkswagen · Powertrain VW's part-load fuel adaptation has maxed out adding fuel on bank 1 – the engine runs lean as… Moderate P1272 Nissan · Powertrain The front air/fuel ratio sensor on bank 1 isn't sending a usable, moving signal to the Nissan… Moderate P1289 Ford · Powertrain The CHT sensor signal on your Ford is stuck near 5 volts, which the PCM reads as an impossibly… Moderate 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 P2002 Powertrain The ECU thinks the diesel particulate filter isn't trapping soot properly — or it can't measure… Moderate 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 P2188 Powertrain At idle, bank 1 gets extra fuel from somewhere the PCM doesn't control; above idle the mixture… Moderate P219A Powertrain One cylinder on bank 1 runs clearly richer or leaner than the others, even if the average looks… Moderate P2201 Powertrain The upstream NOx sensor still communicates, but its readings don't match what the ECM expects. Moderate P2263 Powertrain Boost isn't tracking its target closely enough: too low, too high or too slow to respond. Moderate P242F Powertrain The DPF is filling up with ash that regeneration can't burn off; it needs cleaning… Moderate P244B Powertrain The DPF is resisting exhaust flow far more than it should – usually a filter packed with soot… Moderate P2453 Powertrain The DPF pressure reading doesn't make sense for the exhaust flow – most often a hose or tube… Moderate P2458 Powertrain A DPF regen took too long or never finished, usually from short trips or exhaust that won't get… Moderate P2459 Powertrain The DPF is regenerating far more often than it should for the miles driven. Moderate P2463 Powertrain The DPF is loaded with more soot than the ECU allows; it needs a regen or cleaning before it… High P2647 Powertrain The VTEC oil pressure switch reports the high-lift rockers engaged while the engine computer… Moderate P3000 Toyota · Powertrain Toyota's hybrid computer flags a fault in the high-voltage battery system and limits hybrid… High P3190 Toyota · Powertrain The hybrid computer asked the gas engine for power and got less than expected. Moderate P3400 Powertrain Cylinder shut-off on bank 1 (AFM, DFM, MDS or VCM) isn't doing what the engine computer… Moderate P3497 Honda · Powertrain Honda's Variable Cylinder Management on the front cylinder bank didn't behave the way the PCM… Moderate