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

P1131 Ford · Powertrain Ford's front O2 sensor on bank 1 stays lean even after the PCM has added all the fuel it… Low P1136 Volkswagen · Powertrain At idle the VW computer is adding the maximum fixed amount of fuel on bank 1 – a classic vacuum… 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 P1151 Ford · Powertrain On a Ford V6 or V8, the front O2 sensor on the bank 2 side stays lean and never switches back… Low P1273 Nissan · Powertrain Nissan's ECM sees the front air/fuel ratio sensor on bank 1 reading lean for too long and flags… Low P1295 Hyundai · Powertrain Hyundai's engine computer no longer trusts the electronic throttle and has cut power as… High P1298 Honda · Powertrain The ELD signal that tells the PCM how much current the car is drawing is stuck too high. Low P1300 Toyota · Powertrain Toyota's ECM fires ignition coil No. 1 but gets no confirmation pulse (IGF) back from its… Moderate P1305 Toyota · Powertrain The igniter in Toyota coil No. 2 stops confirming its sparks, often only once the engine is hot. Moderate P1310 Toyota · Powertrain No spark confirmation from one Toyota coil: No. 3 on four-cylinders, but a different coil… Moderate P1320 Nissan · Powertrain The Nissan ECM isn't seeing the ignition primary signal it expects while the engine cranks… Moderate P1336 Ford · Powertrain The Ford PCM sees the cam and crank signals out of step, usually from a mistimed or worn cam… Moderate P1340 Volkswagen · Powertrain The cam signal no longer lines up with the crank signal – often a jumped belt or stretched… High P1345 Chevrolet · Powertrain The cam signal is out of step with the crank signal; on Vortec engines usually a mis-set… 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 P1361 Honda · Powertrain The top dead center (TDC) sensor signal keeps dropping out for a moment while the engine… Moderate P1380 Chevrolet · Powertrain A misfire was detected, and the ABS module couldn't supply rough-road data to confirm it wasn't… Moderate P1381 Chevrolet · Powertrain A misfire was detected while the PCM had lost contact with the ABS module that supplies… Moderate P1399 Honda · Powertrain An older Honda's PCM counted misfires that jump between cylinders instead of staying in one. Moderate P1401 Ford · Powertrain The Ford DPFE sensor that measures EGR flow is sending a voltage above anything it should… Low P1404 Chevrolet · Powertrain The electric EGR valve on a Chevy isn't fully closing when the PCM commands it shut. Low P1406 Ford · Powertrain The hose between Ford's DPFE sensor and the EGR-valve side of the orifice is off, leaking… Low P1441 Chevrolet · Powertrain Engine vacuum is reaching the fuel tank even though the PCM has the EVAP purge valve turned off. Low P1444 Nissan · Powertrain Nissan's ECM sees fuel vapor flowing to the engine while the purge valve is supposed to be shut. Low P1506 Ford · Powertrain Ford's idle speed stays above target even though the PCM has closed the idle air valve as far… Low P1507 Ford · Powertrain Ford's idle keeps dropping below target even with the idle air valve commanded wide open, often… Low P1516 Chevrolet · Powertrain The electronic throttle didn't move to where the computer commanded, so the engine drops into… Moderate P1519 Honda · Powertrain The PCM found a fault in the idle air control valve (IACV) circuit on a Honda with a cable… Moderate