Speed & Idle Control Trouble Codes: List & Fixes

P0505 Powertrain The engine computer can't hold idle speed where it wants it – usually a dirty or sticking idle… Low P0507 Powertrain The engine idles faster than the computer's target – most often extra air is sneaking… Low P0500 Powertrain The engine computer lost its vehicle speed signal – speedometer, shifting and cruise control… Moderate P0501 Powertrain A speed signal exists, but it doesn't match what engine rpm, gear and other sensors say the car… Low P0503 Powertrain The speed signal jumps, spikes or reads impossibly high – usually electrical noise or a loose… Low P0506 Powertrain The engine idles below the computer's target even with idle air opened up – usually a gummed-up… Low

P1603 Toyota · Powertrain Toyota's ECM logged that the engine stopped by itself while running, without the key being… Moderate P1605 Toyota · Powertrain On newer Toyotas the idle sagged below about 400 rpm; on some older ones it flags the ECM's… Low P2100 Powertrain The computer can't push current through the throttle motor – the circuit to the throttle body… High P2101 Powertrain The throttle plate isn't reaching the position the computer asks for, fast enough or accurately… Moderate P2102 Powertrain Too little current or voltage reaches the throttle motor – usually resistance in the feed, not… Moderate P2103 Powertrain The throttle motor circuit draws too much current – a short, a shorted motor or a plate that… Moderate P2104 Powertrain A fail-safe has locked the engine at idle and the gas pedal no longer works – another code… High P2105 Powertrain The engine computer shut the engine off on purpose because it could no longer control… Critical P2106 Powertrain Reduced-power limp mode: the PCM caught a throttle or pedal fault – look for the companion code. Moderate P2107 Powertrain The processor supervising the electronic throttle failed its self-check – a computer fault, not… High P2108 Powertrain The throttle control module isn't performing as expected – check its power, data link… Moderate P2109 Powertrain The closed-throttle reading no longer matches what the computer learned – usually carbon… Low P2110 Powertrain The PCM is capping engine speed with fuel cut-off because it can't fully trust or close… Moderate P2111 Powertrain The throttle plate stayed more open than commanded – a real safety concern until you know why. High P2112 Powertrain The PCM asked the throttle to open, but it stayed shut – the engine can't get air, so it bogs… High P2118 Powertrain The throttle motor is drawing more or less current than the PCM expects to hold the plate where… Moderate P2119 Powertrain The throttle plate isn't reaching the position the PCM commands, or won't spring back to its… Moderate P2120 Powertrain The PCM lost a usable signal from the main gas pedal sensor, often only for a moment. Moderate P2121 Powertrain The main gas pedal signal stays within normal voltage but moves in a way a real pedal can't. Moderate P2122 Powertrain The main gas pedal sensor reads close to 0 volts, below anything a working pedal produces… Moderate P2123 Powertrain The main gas pedal sensor reads near its full 5-volt supply or higher, even with your foot off… Moderate P2125 Powertrain The PCM lost a valid signal from the second, cross-check sensor in the gas pedal. Moderate P2127 Powertrain The second gas pedal sensor dropped below its minimum voltage, so the PCM can't verify pedal… Moderate P2128 Powertrain The second gas pedal sensor reads above its allowed maximum, so the pedal position can't be… Moderate P2135 Powertrain The two position signals inside the throttle body disagree, so the PCM can no longer trust… Moderate P2138 Powertrain The two sensors in the gas pedal report different pedal positions, so the PCM limits throttle… Moderate P2176 Powertrain The PCM hasn't stored where the closed throttle sits, usually after a battery disconnect… Low