OBD2 Fault Code Library

Browse the full AI-Diagnostics-Pro fault code library. Every link below points to a crawlable code page with UK repair-cost context, MOT relevance, and next-step guidance.

Start with the exact code from your scanner, then follow the related-code links on each page if you need to compare similar faults or spot patterns that often appear together.

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Powertrain codesChassis codesBody codes

Powertrain codes

Engine, emissions, fuel, ignition, turbo, cooling and transmission-related OBD2 fault codes.

P0A0F
Drive Motor A Performance
P0A09
DC/DC Converter Status Circuit Low
P0BBE
Hybrid Battery Voltage System Isolation Fault
P0010
A Camshaft Position Actuator Circuit Bank 1
P0011
A Camshaft Position Timing Over-Advanced Bank 1
P11A0
EGR Cooler Bypass Control Circuit
P0012
A Camshaft Position Timing Over-Retarded Bank 1
P0014
B Camshaft Position Timing Over-Advanced Bank 1
P0016
Crankshaft/Camshaft Position Correlation Bank 1 Sensor A
P20E8
Reductant Injection Performance
P0087
Fuel Rail/System Pressure Too Low
P0088
Fuel Rail/System Pressure Too High
P0089
Fuel Pressure Regulator Performance
P0093
Fuel System Leak Detected Large Leak
P0101
Mass Air Flow Circuit Range/Performance Problem
P0102
Mass Air Flow Circuit Low Input
P0103
Mass Air Flow Circuit High Input
P0113
Intake Air Temperature Circuit High Input
P0115
Engine Coolant Temperature Circuit Malfunction
P0116
Engine Coolant Temperature Circuit Range/Performance
P0117
Engine Coolant Temperature Circuit Low Input
P0118
Engine Coolant Temperature Circuit High Input
P0120
Throttle Position Sensor Circuit Malfunction
P0121
Throttle Position Sensor Circuit Range/Performance
P0128
Coolant Temperature Below Thermostat Regulating Temperature
P0130
O2 Sensor Circuit Malfunction Bank 1 Sensor 1
P0131
O2 Sensor Circuit Low Voltage Bank 1 Sensor 1
P0132
O2 Sensor Circuit High Voltage Bank 1 Sensor 1
P0133
O2 Sensor Circuit Slow Response Bank 1 Sensor 1
P0135
O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 1
P0136
O2 Sensor Circuit Malfunction Bank 1 Sensor 2
P0137
O2 Sensor Circuit Low Voltage Bank 1 Sensor 2
P0138
O2 Sensor Circuit High Voltage Bank 1 Sensor 2
P0141
O2 Sensor Heater Circuit Malfunction Bank 1 Sensor 2
P0150
O2 Sensor Circuit Malfunction Bank 2 Sensor 1
P0155
O2 Sensor Heater Circuit Malfunction Bank 2 Sensor 1
P0161
O2 Sensor Heater Circuit Malfunction Bank 2 Sensor 2
P0171
System Too Lean Bank 1
P0172
System Too Rich Bank 1
P0174
System Too Lean Bank 2
P0175
System Too Rich Bank 2
P0190
Fuel Rail Pressure Sensor Circuit Malfunction
P0191
Fuel Rail Pressure Sensor Circuit Range/Performance
P203F
Reductant Level Sensor Performance
P0217
Engine Overtemp Condition
P0234
Turbo/Supercharger Overboost Condition
P0235
Turbocharger Boost Sensor A Circuit Malfunction
P0236
Turbocharger Boost Sensor A Circuit Range/Performance
P0299
Turbo/Supercharger Underboost Condition
P0300
Random/Multiple Cylinder Misfire Detected
P0301
Cylinder 1 Misfire Detected
P0302
Cylinder 2 Misfire Detected
P0303
Cylinder 3 Misfire Detected
P0304
Cylinder 4 Misfire Detected
P0305
Cylinder 5 Misfire Detected
P0306
Cylinder 6 Misfire Detected
P0316
Misfire Detected on Startup First 1000 Revolutions
P0335
Crankshaft Position Sensor A Circuit Malfunction
P0336
Crankshaft Position Sensor A Circuit Range/Performance
P0340
Camshaft Position Sensor Circuit Malfunction Bank 1
P0341
Camshaft Position Sensor Circuit Range/Performance Bank 1
P0345
Camshaft Position Sensor A Circuit Bank 2
P0351
Ignition Coil A Primary/Secondary Circuit Malfunction
P0352
Ignition Coil B Primary/Secondary Circuit Malfunction
P0353
Ignition Coil C Primary/Secondary Circuit Malfunction
P0354
Ignition Coil D Primary/Secondary Circuit Malfunction
P0400
Exhaust Gas Recirculation Flow Malfunction
P0401
Exhaust Gas Recirculation Flow Insufficient Detected
P0402
Exhaust Gas Recirculation Flow Excessive Detected
P0403
Exhaust Gas Recirculation Circuit Malfunction
P0411
Secondary Air Injection System Incorrect Flow Detected
P0420
Catalyst System Efficiency Below Threshold Bank 1
P0421
Warm Up Catalyst Efficiency Below Threshold Bank 1
P0430
Catalyst System Efficiency Below Threshold Bank 2
P0431
Warm Up Catalyst Efficiency Below Threshold Bank 2
P0440
Evaporative Emission Control System Malfunction
P0442
Evaporative Emission System Leak Detected Small Leak
P0446
Evaporative Emission Control System Vent Control Circuit
P0455
Evaporative Emission System Leak Detected Large Leak
P0456
Evaporative Emission System Leak Detected Very Small Leak
P0457
Evaporative Emission System Leak Detected Fuel Cap Loose or Off
P0480
Cooling Fan 1 Control Circuit Malfunction
P0505
Idle Control System Malfunction
P0506
Idle Control System RPM Lower Than Expected
P0507
Idle Control System RPM Higher Than Expected
P0520
Engine Oil Pressure Sensor/Switch Circuit Malfunction
P0521
Engine Oil Pressure Sensor/Switch Range/Performance
P0522
Engine Oil Pressure Sensor/Switch Low Voltage
P0562
System Voltage Low
P0563
System Voltage High
P0700
Transmission Control System Malfunction
P0715
Input/Turbine Speed Sensor Circuit Malfunction
P0720
Output Speed Sensor Circuit Malfunction
P0730
Incorrect Gear Ratio
P0741
Torque Converter Clutch Circuit Performance or Stuck Off
P0750
Shift Solenoid A Malfunction
P0755
Shift Solenoid B Malfunction
P1610
NATS Malfunction Immobiliser Fault
P2002
Diesel Particulate Filter Efficiency Below Threshold Bank 1
P2003
Diesel Particulate Filter Restriction Ash Accumulation Bank 1
P2200
NOx Sensor Circuit Bank 1
P2201
NOx Sensor Circuit Range/Performance Bank 1
P2459
Diesel Particulate Filter Regeneration Frequency

Chassis codes

ABS, wheel-speed, traction-control and other chassis or braking-system related codes.

C0035
Left Front Wheel Speed Sensor Circuit
C0040
Right Front Wheel Speed Sensor Circuit
C0045
Left Rear Wheel Speed Sensor Circuit
C0050
Right Rear Wheel Speed Sensor Circuit
C0300
Rear Propshaft Speed Sensor Circuit Malfunction
C0750
Tyre Pressure Monitoring System Sensor Fault

Body codes

Airbag, restraint-system and body-electronics fault codes.

B0001
Driver Frontal Stage 1 Deployment Control
B0051
Passenger Frontal Stage 1 Deployment Control