Look up a fault code
A check engine light gives you a code, not an answer. Search or browse all9,533 generic OBD-II codes — every one has its own page with symptoms, likely causes and the parts involved.
Type at least two characters. Partial codes and wildcards (* and ?) work.
Codes we see most
These carry notes from our own bays on what the code usually means on an Alfa Romeo or a Ford EcoBoost.
- P0011"A" Camshaft Position - Timing Over-Advanced or System Performance (Bank 1)
- P0014"B" Camshaft Position - Timing Over-Advanced (Bank 1)
- P0016Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor A)
- P0030HO2S Heater Control Circuit (Bank 1 Sensor 1)
- P0087Fuel Rail/System Pressure Too Low
- P0100Mass or Volume Air Flow Circuit Malfunction
- P0101Mass or Volume Air Flow Circuit Range/Performance
- P0106Manifold Absolute Pressure Sensor Range/Performance
- P0113Intake Air Temperature Sensor High Input
- P0128Coolant Thermostat Below Regulating Temperature
- P0133O2 Sensor Slow Response (Bank 1, Sensor 1)
- P0171System Too Lean (Bank 1)
- P0172System Too Rich (Bank 1)
- P0174System Too Lean (Bank 2)
- P0175System Too Rich (Bank 2)
- P0191Fuel Rail Pressure Sensor Circuit Range / Performance
- P0193Fuel Rail Pressure Sensor Circuit High Input
- P0217Engine Coolant Over Temperature Condition
- P0234Turbocharger/Supercharger "A" Overboost Condition
- P0243Turbocharger/Supercharger Wastegate Actuator A
- P0299Turbocharger/Supercharger "A" Underboost Condition
- P0300Random/Multiple Cylinder Misfire Detected
- P0301Cylinder 1 Misfire Detected
- P0302Cylinder 2 Misfire Detected
- P0303Cylinder 3 Misfire Detected
- P0304Cylinder 4 Misfire Detected
- P0316Engine Misfire Detected on Startup (First 1000 Revolutions)
- P0324Knock/Combustion Vibration Control System Error
- P0335Crankshaft Position Sensor "A" Circuit Malfunction
- P0340Camshaft Position Sensor "A" Circuit (Bank 1 or Single Sensor)
- P0355Ignition Coil "E" Primary/Secondary Circuit
- P0401Exhaust Gas Recirculation Flow Insufficient Detected
- P0420Catalyst System Efficiency Below Threshold (Bank 1)
- P0430Catalyst System Efficiency Below Threshold (Bank 2)
- P0442Evaporative Emission System Leak Detected (Small Leak)
- P0456Evaporative Emission System Leak Detected (Very Small Leak)
- P2004Intake Manifold Runner Control Stuck Open (Bank 1)
- U0100Lost Communication with ECM/PCM "A"
Browse every code
All 9,533 codes, grouped by range. Every code has its own page.
B0xxx — 323 codes
Body codes — airbags, restraints, climate and interior systems.
C0xxx — 626 codes
Chassis codes — ABS, traction control, steering and suspension.
P0xxx — 3,705 codes
Generic powertrain codes — engine, fuel, ignition, emissions and transmission.
P2xxx — 3,495 codes
Generic powertrain codes — injector, sensor and emissions circuits.
U0xxx — 1,055 codes
Network and communication codes — modules losing contact with each other.