From Faq
P0500 - P0599 Speed, Idle Control & Aux Inputs
P0500 Vehicle Speed Sensor "A"
P0501 Vehicle Speed Sensor "A" Range/Performance
P0502 Vehicle Speed Sensor "A" Circuit Low Input
P0503 Vehicle Speed Sensor "A" Intermittent/Erratic/High
P0504 Brake Switch "A"/"B" Correlation
P0505 Idle Air Control System
P0506 Idle Air Control System RPM Lower Than Expected
P0507 Idle Air Control System RPM Higher Than Expected
P0508 Idle Air Control System Circuit Low
P0509 Idle Air Control System Circuit High
P0510 Closed Throttle Position Switch
P0511 Idle Air Control Circuit
P0512 Starter Request Circuit
P0513 Incorrect Immobilizer Key
P0514 Battery Temperature Sensor Circuit Range/Performance
P0515 Battery Temperature Sensor Circuit
P0516 Battery Temperature Sensor Circuit Low
P0517 Battery Temperature Sensor Circuit High
P0518 Idle Air Control Circuit Intermittent
P0519 Idle Air Control System Performance
P0520 Engine Oil Pressure Sensor/Switch Circuit
P0521 Engine Oil Pressure Sensor/Switch Range/Performance
P0522 Engine Oil Pressure Sensor/Switch Low Voltage
P0523 Engine Oil Pressure Sensor/Switch High Voltage
P0524 Engine Oil Pressure Too Low
P0525 Cruise Control Servo Control Circuit Range/Performance
P0526 Fan Speed Sensor Circuit
P0527 Fan Speed Sensor Circuit Range/Performance
P0528 Fan Speed Sensor Circuit No Signal
P0529 Fan Speed Sensor Circuit Intermittent
P0530 A/C Refrigerant Pressure Sensor "A" Circuit
P0531 A/C Refrigerant Pressure Sensor "A" Circuit Range/Performance
P0532 A/C Refrigerant Pressure Sensor "A" Circuit Low
P0533 A/C Refrigerant Pressure Sensor "A" Circuit High
P0534 Air Conditioner Refrigerant Charge Loss
P0535 A/C Evaporator Temperature Sensor Circuit
P0536 A/C Evaporator Temperature Sensor Circuit Range/Performance
P0537 A/C Evaporator Temperature Sensor Circuit Low
P0538 A/C Evaporator Temperature Sensor Circuit High
P0539 A/C Evaporator Temperature Sensor Circuit Intermittent
P0540 Intake Air Heater "A" Circuit
P0541 Intake Air Heater "A" Circuit Low
P0542 Intake Air Heater "A" Circuit High
P0543 Intake Air Heater "A" Circuit Open
P0544 Exhaust Gas Temperature Sensor Circuit Bank 1 Sensor 1
P0545 Exhaust Gas Temperature Sensor Circuit Low Bank 1 Sensor 1
P0546 Exhaust Gas Temperature Sensor Circuit High Bank 1 Sensor 1
P0547 Exhaust Gas Temperature Sensor Circuit Bank 2 Sensor 1
P0548 Exhaust Gas Temperature Sensor Circuit Low Bank 2 Sensor 1
P0549 Exhaust Gas Temperature Sensor Circuit High Bank 2 Sensor 1
P0550 Power Steering Pressure Sensor/Switch Circuit
P0551 Power Steering Pressure Sensor/Switch Circuit Range/Performance
P0552 Power Steering Pressure Sensor/Switch Circuit Low Input
P0553 Power Steering Pressure Sensor/Switch Circuit High Input
P0554 Power Steering Pressure Sensor/Switch Circuit Intermittent
P0555 Brake Booster Pressure Sensor Circuit
P0556 Brake Booster Pressure Sensor Circuit Range/Performance
P0557 Brake Booster Pressure Sensor Circuit Low Input
P0558 Brake Booster Pressure Sensor Circuit High Input
P0559 Brake Booster Pressure Sensor Circuit Intermittent
P0560 System Voltage
P0561 System Voltage Unstable
P0562 System Voltage Low
P0563 System Voltage High
P0564 Cruise Control Multi-Function Input "A" Circuit
P0565 Cruise Control On Signal
P0566 Cruise Control Off Signal
P0567 Cruise Control Resume Signal
P0568 Cruise Control Set Signal
P0569 Cruise Control Coast Signal
P0570 Cruise Control Accelerate Signal
P0571 Brake Switch "A" Circuit
P0572 Brake Switch "A" Circuit Low
P0573 Brake Switch "A" Circuit High
P0574 Cruise Control System - Vehicle Speed Too High
P0575 Cruise Control Input Circuit
P0576 Cruise Control Input Circuit Low
P0577 Cruise Control Input Circuit High
P0578 Cruise Control Multi-Function Input "A" Circuit Stuck
P0579 Cruise Control Multi-Function Input "A" Circuit Range/Performance
P0580 Cruise Control Multi-Function Input "A" Circuit Low
P0581 Cruise Control Multi-Function Input "A" Circuit High
P0582 Cruise Control Vacuum Control Circuit/Open
P0583 Cruise Control Vacuum Control Circuit Low
P0584 Cruise Control Vacuum Control Circuit High
P0585 Cruise Control Multi-Function Input "A"/"B" Correlation
P0586 Cruise Control Vent Control Circuit/Open
P0587 Cruise Control Vent Control Circuit Low
P0588 Cruise Control Vent Control Circuit High
P0589 Cruise Control Multi-Function Input "B" Circuit
P0590 Cruise Control Multi-Function Input "B" Circuit Stuck
P0591 Cruise Control Multi-Function Input "B" Circuit Range/Performance
P0592 Cruise Control Multi-Function Input "B" Circuit Low
P0593 Cruise Control Multi-Function Input "B" Circuit High
P0594 Cruise Control Servo Control Circuit/Open
P0595 Cruise Control Servo Control Circuit Low
P0596 Cruise Control Servo Control Circuit High
P0597 Thermostat Heater Control Circuit/Open
P0598 Thermostat Heater Control Circuit Low
P0599 Thermostat Heater Control Circuit High
