Rough idle: Codes, Causes & Fixes

P0174 Powertrain The cylinder bank without cylinder 1 is running lean even with the maximum fuel correction… Moderate P0101 Powertrain The MAF sensor's airflow reading doesn't match what the engine computer expects… Low P0171 Powertrain The engine computer is adding the maximum extra fuel it's allowed on bank 1 and still sees… Moderate 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 P0302 Powertrain Cylinder 2 keeps misfiring. On inline engines it's a middle cylinder, so rule out coolant… Moderate

P0130 Powertrain The upstream oxygen sensor on bank 1 sent a signal the engine computer could not make sense of. Low P0131 Powertrain The upstream oxygen sensor on bank 1 keeps reporting a voltage so low that it reads as a lean… Low P0132 Powertrain The upstream oxygen sensor on bank 1 reads too high: the engine is running rich or the signal… Moderate P0150 Powertrain The upstream O2 sensor circuit on bank 2 is sending readings the ECU can't use, usually wiring… Low P0152 Powertrain Bank 2's front O2 sensor is pinned high – usually voltage leaking in from its heater wire… Moderate P0154 Powertrain Bank 2's front O2 sensor never started switching; the ECU sees only a flat voltage from it. Low P0170 Powertrain Bank 1 fuel correction is far outside its normal window, lean or rich, and the ECU won't say… Moderate P0171 Powertrain The engine computer is adding the maximum extra fuel it's allowed on bank 1 and still sees… 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 P0174 Powertrain The cylinder bank without cylinder 1 is running lean even with the maximum fuel correction… Moderate P0175 Powertrain Bank 2 is still running rich even though the PCM is already cutting fuel on that side as far as… Moderate P0191 Powertrain The rail pressure reading is electrically valid but doesn't make sense for how the engine… Moderate P0200 Powertrain The ECU found a fault in the injector control circuits that it can't pin on one cylinder, often… High P0201 Powertrain The ECU sees an open or faulty electrical circuit to injector 1, so cylinder 1 is probably… Moderate P0202 Powertrain Injector 2's circuit is open or out of range; on an inline-four it's a middle cylinder under… Moderate P0203 Powertrain The ECU sees no normal electrical response from injector 3: its coil, its wiring or its driver… Moderate P0204 Powertrain The circuit to injector 4 is open or out of range; on most transverse engines that's… Moderate P0205 Powertrain The ECU sees a broken or faulty electrical circuit to the cylinder 5 injector, so that cylinder… Moderate P0206 Powertrain Injector 6's circuit is open or faulty. On an inline-six that's the rear cylinder, tucked under… Moderate P0207 Powertrain The ECU lost normal control of injector 7, which only exists on V8 and larger engines. Moderate P0208 Powertrain The circuit to injector 8, the rear cylinder on bank 2 of a V8, is open or doesn't respond… Moderate P0219 Powertrain The engine was spun faster than its maximum allowed rpm, usually by a missed shift or wheelspin. Moderate P0221 Powertrain The second throttle angle signal leaves its window or stops following the plate, so power… Moderate P0263 Powertrain Cylinder 1 is producing noticeably more or less power than the others, beyond what fuel trim… Moderate P0266 Powertrain The engine computer can't even out cylinder 2 with fuel corrections; its balance rate is past… Moderate P0269 Powertrain Cylinder 3 isn't pulling its weight, or is pulling too hard, and the fuel correction for it… Moderate P0272 Powertrain The ECU can't balance cylinder 4 against the rest anymore; its fuel correction is outside… Moderate P0275 Powertrain The fuel correction for cylinder 5 is past its limit. Only engines with five or more cylinders… Moderate P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High