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Diagnostic Codes List

This page provides a structured reference list of automotive Diagnostic Trouble Codes (DTCs) used by modern vehicle onboard diagnostic systems.

Diagnostic codes are generated by the ECU when a fault is detected in the engine, transmission, emissions system, vehicle network, or other electronic control systems. Each code represents a specific fault condition and serves as the starting point for vehicle diagnostics and troubleshooting.

This Diagnostic Codes List allows technicians and automotive professionals to browse fault codes by system category, quickly identify code meanings, and access detailed diagnostic information for each individual code.

By selecting a specific diagnostic code, you can view in-depth explanations including fault descriptions, affected systems, common causes, diagnostic procedures, and recommended inspection steps based on real-world diagnostic scenarios.

This list is designed to support efficient fault identification and accurate diagnosis using professional diagnostic tools, live data analysis, and vehicle-specific diagnostic workflows.

Select by System

P0444

Diagnostic trouble code P0444 indicates an open circuit in the EVAP purge valve control

P0445

Diagnostic trouble code P0445 indicates a short circuit in the EVAP purge valve control

P0447

Diagnostic trouble code P0447 indicates an open circuit in the EVAP vent control valve

P0448

Diagnostic trouble code P0448 indicates a short circuit in the EVAP vent control valve

P0496

Diagnostic trouble code P0496 indicates EVAP system flow during non-purge conditions

P0497

Diagnostic trouble code P0497 indicates low purge flow in the EVAP system

P0498

Diagnostic trouble code P0498 indicates low voltage in the EVAP vent valve control circuit

P0499

Diagnostic trouble code P0499 indicates high voltage in the EVAP vent valve control circuit

P0520

Diagnostic trouble code P0520 indicates a malfunction in the engine oil pressure sensor circuit

P0521

Diagnostic trouble code P0521 indicates an engine oil pressure sensor range or performance issue

P0522

Diagnostic trouble code P0522 indicates low input from the engine oil pressure sensor

C0300

Diagnostic trouble code C0300 indicates a malfunction in the transfer case control system

C0315

Diagnostic trouble code C0315 indicates an incorrect yaw rate or acceleration sensor calibration

U0122

Diagnostic trouble code U0122 indicates a loss of communication with the vehicle dynamics control module

U0141

Diagnostic trouble code U0141 indicates a loss of communication with the climate control module

U0164

Diagnostic trouble code U0164 indicates a loss of communication with the HVAC control module

U0184

Diagnostic trouble code U0184 indicates a loss of communication with the radio or infotainment control module

B1370

Diagnostic trouble code B1370 indicates an ignition switch circuit malfunction

B2100

Diagnostic trouble code B2100 indicates a malfunction in the mirror or seat memory control circuit

B2200

Diagnostic trouble code B2200 indicates a malfunction in the instrument cluster control circuit

B2500

Diagnostic trouble code B2500 indicates a malfunction in the courtesy lamp or interior lighting circuit

P0355

Diagnostic trouble code P0355 indicates a malfunction in ignition coil E circuit

P0356

Diagnostic trouble code P0356 indicates a malfunction in ignition coil F circuit

P0365

Diagnostic trouble code P0365 indicates a malfunction in camshaft position sensor B circuit (Bank 1)

P0366

Diagnostic trouble code P0366 indicates a range or performance issue with camshaft position sensor B

P0367

Diagnostic trouble code P0367 indicates low input from camshaft position sensor B

P0368

Diagnostic trouble code P0368 indicates high input from camshaft position sensor B

P0370

Diagnostic trouble code P0370 indicates a malfunction in the timing reference high resolution signal

P0505

Diagnostic trouble code P0505 indicates a malfunction in the idle air control (IAC) system

P0506

Diagnostic trouble code P0506 indicates idle speed is lower than expected

P0507

Diagnostic trouble code P0507 indicates idle speed is higher than expected

P0510

Diagnostic trouble code P0510 indicates a closed throttle position switch malfunction

P2100

Diagnostic trouble code P2100 indicates a malfunction in the throttle actuator control motor circuit

P2101

Diagnostic trouble code P2101 indicates throttle actuator control motor range or performance issues

P2102

Diagnostic trouble code P2102 indicates low input in the throttle actuator control motor circuit

P2103

Diagnostic trouble code P2103 indicates high input in the throttle actuator control motor circuit

P2110

Diagnostic trouble code P2110 indicates the throttle actuator control system has limited engine RPM

P2111

Diagnostic trouble code P2111 indicates the throttle actuator is stuck open

P2112

Diagnostic trouble code P2112 indicates the throttle actuator is stuck closed

P2118

Diagnostic trouble code P2118 indicates a throttle actuator control motor current range issue

P2120

Diagnostic trouble code P2120 indicates a malfunction in the throttle position sensor circuit

P2122

Diagnostic trouble code P2122 indicates low input from the throttle position sensor

P2123

Diagnostic trouble code P2123 indicates high input from the throttle position sensor

P2135

Diagnostic trouble code P2135 indicates a correlation error between throttle position sensors A and B

P2138

Diagnostic trouble code P2138 indicates a correlation error between accelerator pedal position sensors

P2148

Diagnostic trouble code P2148 indicates a malfunction in the fuel injector group control circuit

P2176

Diagnostic trouble code P2176 indicates the throttle actuator control system could not learn the idle position

P2187

Diagnostic trouble code P2187 indicates a lean condition at idle on Bank 1

P0480

Diagnostic trouble code P0480 indicates a malfunction in the cooling fan control circuit

P0481

Diagnostic trouble code P0481 indicates a malfunction in cooling fan 2 control circuit

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