This section covers OBD-II codes P2500 to P2599, which are primarily related to Vehicle or idle speed control.

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P2500Alternator warning lamp, L-terminal – circuit low
P2501Alternator warning lamp, L-terminal – circuit high
P2502Charging system voltage
P2503Charging system – voltage low
P2504Charging system – voltage high
P2505Engine control module (ECM) – supply voltage
P2506Engine control module (ECM) – supply voltage, range/performance problem
P2507Engine control module (ECM)- supply voltage low
P2508Engine control module (ECM) – supply voltage high
P2509Engine control module (ECM) – supply voltage, intermittent
P250AEngine oil level sensor – circuit malfunction
P250ALong term fuel trim (LTFT)- range/performance problem
P250BEngine oil level sensor- circuit range/performance
P250CEngine oil level sensor- circuit low
P250DEngine oil level sensor – circuit high
P250EEngine oil level sensor – circuit intermittent/erratic
P250FEngine oil level too low
P2510Engine control (EC) relay, sense circuit – range/performance problem
P2510Power take-off (PTO), engine shut-down – open circuit
P2511Engine control (EC) relay, sense circuit – circuit intermittent
P2512Event data recorder request – open circuit
P2513Event data recorder request – circuit low
P2514Event data recorder request – circuit high
P2515A/C refrigerant pressure sensor B – circuit malfunction
P2516A/C refrigerant pressure sensor B – range/performance problem
P2517AIC refrigerant pressure sensor B – circuit low
P2518A/C refrigerant pressure sensor B – circuit high
P2519A/C request A – circuit malfunction
P251APower take-off (PTO) enable switch – open circuit
P251BPower take-off (PTO) enable switch – circuit low
P251CPower take-off (PTO) enable switch – circuit high
P251EPower take-off (PTO)- engine shut-down- circuit low
P251FPower take-off (PTO) monitoring, engine shut-off control – circuit high
P2520AJC request A – circuit low
P2521AJC request A – circuit high
P2522AJC request B – circuit malfunction
P2523AJC request B – circuit low
P2524AJC request B – circuit high
P2525Vacuum reservoir pressure sensor – circuit malfunction
P2526Vacuum reservoir pressure sensor – range/performance problem
P2527Vacuum reservoir pressure sensor- circuit low
P2528Vacuum reservoir pressure sensor – circuit high
P2529Vacuum reservoir pressure sensor – circuit intermittent
P252AEngine oil quality sensor – circuit malfunction
P252BEngine oil quality sensor – circuit range/performance
P252CEngine oil quality sensor – circuit low
P252DEngine oil quality sensor – circuit high
P252EEngine oil quality sensor – circuit intermittent/erratic
P252FEngine oil level too high
P2530Ignition switch, ON position – circuit malfunction
P2531Ignition switch, ON position – circuit low
P2532Ignition switch, ON position – circuit high
P2533Ignition switch, ON/start position -circuit malfunction
P2534Ignition switch, ON/start position – circuit low
P2535Ignition switch, ON/start position – circuit high
P2536Ignition switch, accessory position – circuit malfunction
P2537Ignition switch, accessory position – circuit low
P2538Ignition switch, accessory position – circuit high
P2539Fuel low pressure sensor – circuit malfunction
P253APower take-off (PTO) monitoring – circuit open
P253BPower take-off (PTO) monitoring- circuit range/performance
P253CPower take-off (PTO) monitoring- circuit low
P253DPower take-off (PTO) monitoring- circuit high
P253EPower take-off (PTO) – sense circuit intermittent malfunction
P253FEngine oil deteriorated
P2540Fuel low pressure sensor – range/performance problem
P2541Fuel low pressure sensor- circuit low
P2542Fuel low pressure sensor – circuit high
P2543Fuel low pressure sensor- circuit intermittent
P2544Torque management request, input signal A – malfunction ·
P2545Torque management request, input signal A – range/performance problem
P2546Torque management request, input signal A – signal low
P2547Torque management request, input signal A – signal high
P2548Torque management request, input signal B – malfunction
P2549Torque management request, input signal B – range/performance problem
P254APower take-off (PTO) speed selector sensor/switch 1 – open circuit
P254BPower take-off (PTO) speed selector sensor/switch 1 – circuit range/performance
P254CPower take-off (PTO) speed selector sensor/switch 1 – circuit low
P254DPower take-off (PTO) speed selector sensor/switch 1 – circuit high
P254EPower take-off (PTO) speed selector sensor/switch 1 – circuit intermittent/erratic
P254FBonnet switch – open circuit
P2550Torque management request, input signal B – signal low
P2551Torque management request, input signal B – signal high
P2552Throttle/fuel inhibit – circuit malfunction
P2553Throttle/fuel inhibit – range/performance problem
P2554Throttle/fuel inhibit – circuit low
P2555Throttle/fuel inhibit – circuit high
P2556Engine coolant ‘low’ sensor/switch – circuit malfunction
P2557Engine coolant ‘low’ sensor/switch – range/performance problem
P2558Engine coolant ‘low’ sensor/switch – circuit low
P2558Power take-off (PTO) speed selector sensor/switch 2 – circuit range/performance
P2559Engine coolant ‘low’ sensor/switch – circuit high
P255APower take-off (PTO) speed selector sensor/switch 2 – open circuit
P255CPower take-off (PTO) speed selector sensor/switch 2 – circuit low
P255DPower take-off (PTO) speed selector sensor/switch 2 – circuit high
P255EPower take-off (PTO) speed selector sensor/switch 2 – circuit intermittent/erratic
P255FAJC request A – circuit range/performance
P2560Engine coolant level low
P2561AJC control module – MIL activation requested
P2562Turbocharger (TC) boost control position sensor – circuit malfunction
P2563Turbocharger (TC) boost control position sensor- range/performance problem
P2564Turbocharger (TC) boost control position sensor – circuit low
P2565Turbocharger {TC) boost control position sensor- circuit high
P2566Turbocharger (TC) boost control position sensor – circuit intermittent
P2567Direct ozone reduction catalytic converter temperature sensor- circuit malfunction
P2568Direct ozone reduction catalytic converter temperature sensor- range/performance problem
P2569Direct ozone reduction catalytic converter temperature sensor – circuit low
P256AEngine idle speed selector sensor/switch – open circuit
P256BEngine idle speed selector sensor/switch – circuit range/performance
P256CEngine idle speed selector sensor/switch – circuit low
P256DEngine idle speed selector sensor/switch – circuit high
P256EEngine idle speed selector sensor/switch – circuit intermittent/erratic
P256FAIC request B – circuit range/performance
P2570Direct ozone reduction catalytic converter temperature sensor – circuit high
P2571Direct ozone reduction catalytic converter temperature sensor- circuit intermittent/erratic
P2572Direct ozone reduction catalytic converter deterioration sensor
P2573Direct ozone reduction catalytic converter deterioration sensor- range/performance problem
P2574Direct ozone reduction catalytic converter deterioration sensor – circuit low
P2575Direct ozone reduction catalytic converter deterioration sensor – circuit high
P2576Direct ozone reduction catalytic converter deterioration sensor – circuit intermittent/erratic
P2577Direct ozone reduction catalytic converter – efficiency below threshold
P2578Turbocharger Speed Sensor Circuit
P2579Turbocharger Speed Sensor Circuit Range/Performance
P257AVacuum reservoir control – open circuit
P257BVacuum reservoir control – circuit low
P257CVacuum reservoir control – circuit high
P257DBonnet switch – circuit range/performance
P257EBonnet switch – circuit low
P257FBonnet switch – circuit high
P2580Turbocharger Speed Sensor Circuit Low
P2581Turbocharger Speed Sensor Circuit High
P2582Turbocharger Speed Sensor Circuit Intermittent
P2583Cruise Control Front Distance Range Sensor
P2584Fuel Additive Control Module Requested MIL Illumination
P2585Fuel Additive Control Module Warning Lamp Request
P2586Turbocharger Boost Control Position Sensor “B” Circuit
P2587Turbocharger Boost Control Position Sensor “B” Circuit Range/Performance
P2588Turbocharger Boost Control Position Sensor “B” Circuit Low
P2589Turbocharger Boost Control Position Sensor “B” Circuit High
P258AVacuum pump – control circuit open
P258BVacuum pump control – range/performance problem
P258CVacuum pump control – circuit low
P258DVacuum pump – control circuit high
P258EPower take-off (PTO) enable switch- performance problem
P258FTorque management request – output signal malfunction
P2590Turbocharger Boost Control Position Sensor “B” Circuit Intermittent/Erratic
P2591Cruise Control Front Distance Range Sensor Left
P2592Cruise Control Front Distance Range Sensor Right
P2593 – P25FFISO/SAE Reserved
P2598Turbocharger Boost Control Position Performance Low Position
P25A2Brake System Control Module “A” Requested MIL Illumination