THE CODE DIRECTORY
Diagnostic code references — Page 21.
Browse canonical reference entries. Each definition keeps its own source and vehicle-applicability limits.
Generic OBD-II
P0539
evaporator temperature signal changes too quickly
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Generic OBD-II
P053A
PCV Heater A Control Circuit /Open
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Generic OBD-II
P053B
Crankcase heater supply remains low when its relay is commanded on
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Generic OBD-II
P053C
Crankcase heater voltage stays high after the relay is switched off
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Generic OBD-II
P053D
PCV Heater A Performance
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Generic OBD-II
P053E
Crankcase Pressure Too High
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Generic OBD-II
P053F
Cold-start fuel pressure is evaluated across the emission-reduction period
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Generic OBD-II
P0540
Intake Air Heater A Circuit
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Generic OBD-II
P0541
Intake Air Heater A Circuit Low
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Generic OBD-II
P0542
Intake Air Heater A Circuit High
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Generic OBD-II
P0543
Intake Air Heater A Circuit Open
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Generic OBD-II
P0544
An exhaust-temperature circuit code can be a model-rationality result
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Generic OBD-II
P0545
EGT sensor 1 low-range feedback and a source limitation
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Generic OBD-II
P0546
EGT sensor 1 above its raw electrical range
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Generic OBD-II
P0547
Bank2 exhaust-temperature plausibility needs the correct operating window
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Generic OBD-II
P0548
Bank2 low EGT voltage is an electrical threshold, not cold exhaust proof
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Generic OBD-II
P0549
A high EGT circuit reading has an explicit warm-up qualification
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Generic OBD-II
P054A
Cold Start B Camshaft Position Timing Over-Advanced Bank 1
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Generic OBD-II
P054B
Cold Start B Camshaft Position Timing Over-Retarded Bank 1
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Generic OBD-II
P054C
Cold Start B Camshaft Position Timing Over-Advanced Bank 2
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Generic OBD-II
P054D
Cold Start B Camshaft Position Timing Over-Retarded Bank 2
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Generic OBD-II
P054E
idle torque-forming fuel quantity below its mapped expectation
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Generic OBD-II
P054F
idle injection quantity above the selected maximum map
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Generic OBD-II
P0550
Titan steering-pressure feedback and idle compensation
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Generic OBD-II
P0551
implausible power-steering pressure switch feedback
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Generic OBD-II
P0552
Power Steering Pressure Sensor/Switch Circuit Low
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Generic OBD-II
P0553
Power Steering Pressure Sensor/Switch Circuit High
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Generic OBD-II
P0554
Power Steering Pressure Sensor/Switch Circuit Intermittent
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Generic OBD-II
P0555
Brake booster vacuum sensor signal outside its electrical range
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Generic OBD-II
P0556
Brake-booster pressure plausibility uses several comparisons
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Generic OBD-II
P0557
Low brake-booster pressure sensor voltage
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Generic OBD-II
P0558
High booster-pressure sensor voltage needs electrical interpretation
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Generic OBD-II
P0559
Brake Booster Pressure Sensor Circuit Intermittent
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Generic OBD-II
P055A
Engine Oil Pressure Sensor/Switch B Circuit
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Generic OBD-II
P055B
Engine Oil Pressure Sensor/Switch B Range/Performance
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Generic OBD-II
P055C
Engine Oil Pressure Sensor/Switch B Low
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Generic OBD-II
P055D
Engine Oil Pressure Sensor/Switch B High
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Generic OBD-II
P055E
Oxygen Sensor Control Module System Voltage
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Generic OBD-II
P055F
Excessive oil pressure is separate from an implausible sensor signal
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Generic OBD-II
P0560
Honda ECM backup supply loses voltage
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Generic OBD-II
P0561
compare the TCM battery feed with its ignition feed
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Generic OBD-II
P0562
Low system voltage measured while the engine is turning
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Generic OBD-II
P0563
High 12-volt system voltage in the ECM monitor
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Generic OBD-II
P0564
Cruise switch voltage falls between valid command ranges
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Generic OBD-II
P0565
Momentary cruise on/off input remains applied too long
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Generic OBD-II
P0566
Cruise Control Off Signal
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Generic OBD-II
P0567
Cruise resume remains decoded as applied
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Generic OBD-II
P0568
Cruise set command stays active beyond its permitted duration
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Generic OBD-II
P0569
Cruise Control Coast Signal
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Generic OBD-II
P056A
Cruise Control Increase Distance Signal
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Generic OBD-II
P056B
Cruise Control Decrease Distance Signal
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Generic OBD-II
P056C
why a persistent cruise-cancel request disables cruise
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Generic OBD-II
P056D
Reductant Control Module System Voltage
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Generic OBD-II
P056E
Cold supercharger malfunction and a possible freezing event
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Generic OBD-II
P056F
Cold Start Turbocharger/Supercharger Boost Control B Performance
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Generic OBD-II
P0570
Cruise Control Accelerate Signal
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Generic OBD-II
P0571
brake-switch plausibility is checked against vehicle movement
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Generic OBD-II
P0572
brake messages disagree in the low-direction monitor
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Generic OBD-II
P0573
brake messages disagree in the high-direction monitor
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Generic OBD-II
P0574
Cruise Control System - Vehicle Speed Too High
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Generic OBD-II
P0575
cruise input data can be present but invalid
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Generic OBD-II
P0576
Cruise Control Input Circuit Low
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Generic OBD-II
P0577
Cruise Control Input Circuit High
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Generic OBD-II
P0578
Cruise Control Multi-Function Input A Circuit Stuck
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Generic OBD-II
P0579
Jeep diesel cruise-switch plausibility versus voltage faults
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Generic OBD-II
P057A
Brake Pedal Position Sensor A Circuit/Open
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Generic OBD-II
P057B
a brake-position signal can fail while remaining in range
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Generic OBD-II
P057C
low brake-position samples and the zero-position fallback
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Generic OBD-II
P057D
a high brake-position input may represent an open circuit
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Generic OBD-II
P057E
erratic brake-position data needs a signal history
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Generic OBD-II
P057F
Battery deterioration monitoring and a missed battery initialization
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Generic OBD-II
P0580
low cruise-switch voltage is architecture dependent
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Generic OBD-II
P0581
high cruise-switch input and a misleading table phrase
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Generic OBD-II
P0582
Cruise Control Vacuum Control Circuit/Open
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Generic OBD-II
P0583
Cruise Control Vacuum Control Circuit Low
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Generic OBD-II
P0584
Cruise Control Vacuum Control Circuit High
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Generic OBD-II
P0585
Cruise Control Multi-Function Input A/B Correlation
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Generic OBD-II
P0586
Cruise Control Vent Control Circuit/Open
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Generic OBD-II
P0587
Cruise Control Vent Control Circuit Low
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Generic OBD-II
P0588
Cruise Control Vent Control Circuit High
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Generic OBD-II
P0589
cruise switch B sits between recognized input ranges
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Generic OBD-II
P058A
battery-monitor internal checks, not a battery-capacity verdict
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Generic OBD-II
P058B
current-monitor performance includes stored sleep-time evidence
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Generic OBD-II
P058C
two internal battery temperatures disagree
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Generic OBD-II
P058D
battery voltage disagrees with the controller reference
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Generic OBD-II
P058E
the battery sensor reports an excessively high internal temperature
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Generic OBD-II
P058F
an extremely low battery-monitor temperature report
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Generic OBD-II
P0590
Cruise Control Multi-Function Input B Circuit Stuck
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Generic OBD-II
P0591
Cruise Control Multi-Function Input B Circuit Range/Performance
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Generic OBD-II
P0592
cruise switch B input in the short-to-ground range
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Generic OBD-II
P0593
cruise switch B input in the short-to-power band
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Generic OBD-II
P0594
Cruise Control Servo Control Circuit/Open
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Generic OBD-II
P0595
Cruise Control Servo Control Circuit Low
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Generic OBD-II
P0596
Cruise Control Servo Control Circuit High
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Generic OBD-II
P0597
Thermostat heater open-circuit classification uses driver status
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Generic OBD-II
P0598
Thermostat heater ground-short status is distinct from an open circuit
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Generic OBD-II
P0599
Thermostat heater circuit remains high in the commanded state
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Generic OBD-II
P059A
Tucson active-air-flap warning traced to sensor solder connections
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Generic OBD-II
P059B
Active Grille Air Shutter A Position Sensor Circuit Range/Performance
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Generic OBD-II
P059C
Active Grille Air Shutter A Position Sensor Circuit High
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These are code references, not a list of confirmed faults on every vehicle. Read the source and applicability notes, then match the exact vehicle, year, engine and scan report.