OBD-II Fault Code Library
Plain-English explanations for common OBD-II trouble codes (DTCs): meaning, symptoms, likely causes, and an approximate Malaysia repair-cost range. General information, not a diagnosis.
Left Front Wheel Speed Sensor Circuit
The left-front wheel speed sensor signal is faulty, affecting ABS/traction systems.
Right Front Wheel Speed Sensor Circuit
A wheel speed sensor fault affecting ABS/traction systems.
Left Rear Wheel Speed Sensor Circuit
A wheel speed sensor fault affecting ABS/traction systems.
Right Rear Wheel Speed Sensor Circuit
A wheel speed sensor fault affecting ABS/traction systems.
ABS Disabled / System Fault
The ABS system has disabled itself due to a fault.
Camshaft Position Actuator Circuit (Bank 1)
The control circuit for the bank 1 intake camshaft timing actuator has a fault.
Camshaft Position 'A' Timing Over-Advanced (Bank 1)
The bank 1 camshaft timing is more advanced than commanded, often an oil-flow or VVT problem.
'A' Camshaft Timing Over-Retarded (Bank 1)
A variable valve timing fault on bank 1, often oil-flow related.
'B' Camshaft Position Actuator Circuit (Bank 1)
A variable valve timing fault on bank 1, often oil-flow related.
'B' Camshaft Timing Over-Advanced (Bank 1)
A variable valve timing fault on bank 1, often oil-flow related.
Crankshaft/Camshaft Position Correlation (Bank 1, Sensor A)
The crankshaft and camshaft are out of sync, which can point to a timing problem.
'A' Camshaft Actuator Circuit (Bank 2)
A variable valve timing fault on bank 2, often oil-flow related.
'A' Camshaft Timing Over-Advanced (Bank 2)
A variable valve timing fault on bank 2, often oil-flow related.
Fuel Rail/System Pressure Too Low
Fuel pressure is below what the engine needs, often a pump or filter problem.
Mass Air Flow Circuit
The mass-airflow sensor circuit has a fault.
Mass Air Flow (MAF) Circuit Range/Performance
The mass-airflow sensor reading is outside the expected range for current conditions.
Mass Air Flow (MAF) Circuit Low Input
The MAF sensor is reporting a lower airflow signal than expected.
Mass Air Flow Circuit High Input
The MAF sensor reports a higher airflow signal than expected.
Manifold Pressure (MAP) Range/Performance
The intake manifold pressure (MAP) sensor reading is out of range.
Manifold Pressure (MAP) Low Input
The intake manifold pressure (MAP) sensor reading is out of range.
Manifold Pressure (MAP) High Input
The intake manifold pressure (MAP) sensor reading is out of range.
Intake Air Temp Sensor Low Input
The intake-air temperature sensor reading is faulty.
Intake Air Temperature (IAT) Sensor High Input
The intake-air temperature sensor is reading abnormally high (or open circuit).
Intake Air Temp Sensor Intermittent
The intake-air temperature sensor reading is faulty.
Engine Coolant Temp Circuit
The coolant temperature sensor reading is faulty, which can affect fueling and fans.
Engine Coolant Temp Range/Performance
The coolant temperature sensor reading is faulty, which can affect fueling and fans.
Engine Coolant Temp Low Input
The coolant temperature sensor reading is faulty, which can affect fueling and fans.
Engine Coolant Temperature (ECT) Sensor High Input
The coolant temperature sensor is reading abnormally high, which can confuse fueling.
Engine Coolant Temp Intermittent
The coolant temperature sensor reading is faulty, which can affect fueling and fans.
Throttle Position Sensor Circuit
The throttle position sensor reading is implausible.
Throttle Position Range/Performance
The throttle position sensor reading is implausible.
Throttle Position Sensor (TPS) Circuit Low Input
The throttle position sensor is reading lower than expected.
Throttle Position Sensor High Input
The throttle position sensor reading is implausible.
Insufficient Coolant Temp for Closed Loop Fuel Control
The engine takes too long to warm up enough for normal fuel control.
Coolant Thermostat Below Regulating Temperature
The engine isn't reaching its normal operating temperature in time, often a stuck-open thermostat.
O2 Sensor Circuit (Bank 1, Sensor 1)
The upstream oxygen sensor on bank 1 isn't behaving as expected.
O2 Sensor Low Voltage (Bank 1, Sensor 1)
The upstream O2 sensor on bank 1 reads persistently low (lean).
O2 Sensor High Voltage (Bank 1, Sensor 1)
The upstream O2 sensor on bank 1 reads persistently high (rich).
O2 Sensor Slow Response (Bank 1, Sensor 1)
The upstream oxygen sensor on bank 1 is responding too slowly, often from age.
O2 Sensor No Activity (Bank 1, Sensor 1)
The upstream O2 sensor on bank 1 isn't responding.
O2 Sensor Heater Circuit (Bank 1, Sensor 1)
The heater in the upstream oxygen sensor on bank 1 isn't working as expected.
O2 Sensor Circuit (Bank 1, Sensor 2)
The downstream O2 sensor on bank 1 has a circuit fault.
O2 Sensor Low Voltage (Bank 1, Sensor 2)
The downstream oxygen sensor on bank 1 reads a low voltage, suggesting a lean reading or sensor fault.
O2 Sensor High Voltage (Bank 1, Sensor 2)
The downstream O2 sensor on bank 1 reads persistently high.
O2 Sensor No Activity (Bank 1, Sensor 2)
The downstream O2 sensor on bank 1 isn't responding.
O2 Sensor Heater Circuit (Bank 1, Sensor 2)
The heater in the downstream oxygen sensor on bank 1 isn't working.
O2 Sensor Circuit (Bank 2, Sensor 1)
The upstream O2 sensor on bank 2 has a circuit fault.
O2 Sensor Heater Circuit (Bank 2, Sensor 1)
The heater in the upstream O2 sensor on bank 2 isn't working.
O2 Sensor No Activity (Bank 2, Sensor 2)
The downstream O2 sensor on bank 2 isn't responding.
O2 Sensor Heater Circuit (Bank 2, Sensor 2)
The heater in the downstream O2 sensor on bank 2 isn't working.
System Too Lean (Bank 1)
The engine is getting too much air or too little fuel on bank 1.
System Too Rich (Bank 1)
The engine is getting too much fuel or too little air on bank 1.
System Too Lean (Bank 2)
The engine is getting too much air or too little fuel on bank 2.
System Too Rich (Bank 2)
The engine is getting too much fuel or too little air on bank 2.
Injector Circuit / Open - Cylinder 1
The electrical circuit for cylinder 1's fuel injector has a fault.
Injector Circuit / Open - Cylinder 2
The electrical circuit for cylinder 2's fuel injector has a fault.
Injector Circuit / Open - Cylinder 3
The electrical circuit for cylinder 3's fuel injector has a fault.
Injector Circuit / Open - Cylinder 4
The electrical circuit for cylinder 4's fuel injector has a fault.
Injector Circuit / Open - Cylinder 5
The electrical circuit for cylinder 5's fuel injector has a fault.
Injector Circuit / Open - Cylinder 6
The electrical circuit for cylinder 6's fuel injector has a fault.
Turbocharger/Supercharger Overboost Condition
The turbo/supercharger is producing more boost than allowed, which can damage the engine.
Turbo/Supercharger Boost Sensor A High
The boost pressure sensor reads higher than expected.
Turbo/Supercharger Wastegate Solenoid A
A fault in the wastegate solenoid that controls boost.
Turbocharger/Supercharger Underboost
The turbo/supercharger is producing less boost than expected.
Random / Multiple Cylinder Misfire Detected
The engine is misfiring across multiple cylinders, which can damage the catalytic converter.
Cylinder 1 Misfire Detected
Cylinder 1 is misfiring, which wastes fuel and can damage the catalytic converter.
Cylinder 2 Misfire Detected
Cylinder 2 is misfiring, which wastes fuel and can damage the catalytic converter.
Cylinder 3 Misfire Detected
Cylinder 3 is misfiring, which wastes fuel and can damage the catalytic converter.
Cylinder 4 Misfire Detected
Cylinder 4 is misfiring, which wastes fuel and can damage the catalytic converter.
Cylinder 5 Misfire Detected
Cylinder 5 is misfiring, which wastes fuel and can damage the catalytic converter.
Cylinder 6 Misfire Detected
Cylinder 6 is misfiring, which wastes fuel and can damage the catalytic converter.
Cylinder 7 Misfire Detected
Cylinder 7 is misfiring, which wastes fuel and can damage the catalytic converter.
Cylinder 8 Misfire Detected
Cylinder 8 is misfiring, which wastes fuel and can damage the catalytic converter.
Knock Sensor 1 Circuit (Bank 1)
The knock sensor that detects engine 'pinging' isn't reporting correctly.
Knock Sensor 2 Circuit (Bank 2)
The bank 2 knock sensor isn't reporting correctly.
Crankshaft Position Sensor 'A' Circuit
The crankshaft position sensor signal is missing or erratic; the engine relies on it to run.
Crankshaft Position Sensor Range/Performance
The crankshaft position signal is erratic.
Camshaft Position Sensor 'A' Circuit
The camshaft position sensor signal is missing or erratic.
Camshaft Position Sensor Range/Performance
The camshaft position signal is erratic.
Camshaft Position Sensor Circuit (Bank 2)
The bank 2 camshaft position sensor has a circuit fault.
Camshaft Position Sensor B Circuit (Bank 1)
The bank 1 'B' camshaft position sensor has a circuit fault.
EGR Flow Malfunction
A fault in the exhaust gas recirculation (EGR) system.
Exhaust Gas Recirculation Flow Insufficient
The EGR system isn't flowing enough exhaust gas back into the engine.
Exhaust Gas Recirculation Flow Excessive
The EGR system is flowing more exhaust gas than expected.
EGR Control Circuit
A fault in the exhaust gas recirculation (EGR) system.
EGR Range/Performance
A fault in the exhaust gas recirculation (EGR) system.
EGR Sensor A Low
A fault in the exhaust gas recirculation (EGR) system.
EGR Sensor A High
A fault in the exhaust gas recirculation (EGR) system.
Secondary Air Injection System
The secondary air injection system has a fault.
Secondary Air Injection System Incorrect Flow
The secondary air injection system (used at cold start) isn't flowing correctly.
Catalyst System Efficiency Below Threshold (Bank 1)
The catalytic converter on bank 1 isn't cleaning the exhaust as well as expected.
Catalyst System Efficiency Below Threshold (Bank 2)
The catalytic converter on bank 2 isn't cleaning the exhaust as well as expected.
EVAP System Malfunction
A fault in the fuel-vapor (EVAP) system; often a cap, hose, or valve.
EVAP Incorrect Purge Flow
A fault in the fuel-vapor (EVAP) system; often a cap, hose, or valve.
EVAP System Leak Detected (Small)
A small leak was found in the fuel-vapor (EVAP) system — often the fuel cap or a hose.
EVAP Purge Control Valve Circuit
A fault in the fuel-vapor (EVAP) system; often a cap, hose, or valve.
EVAP Vent Control Circuit
The vent valve in the EVAP system isn't responding correctly.
EVAP Vent Valve/Solenoid Circuit
A fault in the fuel-vapor (EVAP) system; often a cap, hose, or valve.
EVAP Pressure Sensor Low
A fault in the fuel-vapor (EVAP) system; often a cap, hose, or valve.
EVAP Pressure Sensor High
A fault in the fuel-vapor (EVAP) system; often a cap, hose, or valve.
Evaporative Emission System Leak (Large)
A large leak was detected in the fuel-vapor (EVAP) system — often a loose or faulty fuel cap.
Evaporative Emission System Leak (Very Small)
A very small leak was detected in the EVAP system.
EVAP Leak (Fuel Cap Loose/Off)
A fault in the fuel-vapor (EVAP) system; often a cap, hose, or valve.
Cooling Fan 1 Control Circuit
A cooling-fan control circuit fault; watch engine temperature.
Cooling Fan 2 Control Circuit
A cooling-fan control circuit fault; watch engine temperature.
EGR Throttle Position Control Range/Performance
The EGR throttle/position control is out of its expected range, often carbon-related on diesels.
Vehicle Speed Sensor 'A'
The vehicle speed signal is missing or implausible.
Vehicle Speed Sensor Range/Performance
The vehicle speed signal is implausible.
Idle Air Control System
The system that controls idle speed isn't keeping idle stable.
Idle Air Control RPM Lower Than Expected
The engine idles lower than the computer expects.
Idle Air Control RPM Higher Than Expected
The engine idles higher than expected.
Engine Oil Pressure Sensor/Switch Range/Performance
The oil pressure sensor reading is out of range — verify real oil pressure as a precaution.
System Voltage Malfunction
The system voltage reading is faulty.
System Voltage Low
The electrical system voltage is lower than normal.
System Voltage High
The electrical system voltage is higher than normal.
PCM / ECM Processor Fault
The engine control module reported an internal processor fault.
Generator Control Circuit
A fault in the alternator (generator) control circuit.
A/C Clutch Relay Control Circuit
A fault in the air-conditioning compressor clutch relay circuit.
Transmission Control System (MIL Request)
The transmission computer has logged a fault and asked for the warning light; look for additional P07xx codes.
Transmission Control Range/Performance
The transmission control system is performing outside its expected range.
Transmission Range Sensor Circuit
The gear-range (PRNDL) sensor signal is faulty.
Transmission Fluid Temp Sensor Circuit
The transmission fluid temperature sensor reading is faulty.
Input/Turbine Speed Sensor Circuit
The transmission input (turbine) speed sensor signal is missing or erratic.
Output Speed Sensor Circuit
The transmission output speed sensor signal is missing or erratic.
Gear 1 Incorrect Ratio
The transmission isn't achieving the correct ratio in gear 1.
Gear 2 Incorrect Ratio
The transmission isn't achieving the correct ratio in gear 2.
Gear 3 Incorrect Ratio
The transmission isn't achieving the correct ratio in gear 3.
Gear 4 Incorrect Ratio
The transmission isn't achieving the correct ratio in gear 4.
Torque Converter Clutch Circuit
The torque converter lock-up clutch circuit isn't working as expected.
Torque Converter Clutch Stuck Off / Performance
The torque converter clutch isn't engaging properly, hurting efficiency.
Torque Converter Clutch Stuck On
A torque converter clutch fault affecting efficiency or shifting.
Torque Converter Clutch Circuit Electrical
A torque converter clutch fault affecting efficiency or shifting.
Shift Solenoid A
A shift solenoid circuit fault affecting gear changes.
Shift Solenoid B
A shift solenoid circuit fault affecting gear changes.
Shift Solenoid C
A shift solenoid circuit fault affecting gear changes.
VVT System / Camshaft Timing (Toyota 1NZ)
Toyota-specific VVT fault, commonly a clogged oil-control-valve (OCV) filter screen rather than the solenoid itself.
Intake Air Flap / IAFM Solenoid (Proton Campro)
Proton Campro-specific: the variable intake (IAFM) flap/solenoid is faulty — often a broken plastic flap causing a vacuum leak.
Startability / Hard-Start Malfunction (Toyota 2NR)
Toyota-documented hard-start code, commonly from carbon build-up on intake valves and the combustion chamber.
Post Catalyst Fuel Trim System Too Lean (Bank 1)
After the catalytic converter, the mixture reads lean on bank 1.
Post Catalyst Fuel Trim System Too Rich (Bank 1)
After the catalytic converter, the mixture reads rich on bank 1.
Throttle Actuator Control Motor Range/Performance
The electronic throttle actuator isn't moving as commanded.
Throttle/Pedal Position Sensor D Low Input
The accelerator pedal position sensor reads implausibly low.
Throttle/Pedal Position Sensor E Low Input
A second accelerator pedal position signal reads implausibly low.
Throttle/Pedal Position Sensor A/B Voltage Correlation
Two throttle/pedal position signals disagree, a safety-relevant fault for drive-by-wire.
Throttle/Pedal Position Sensor D/E Correlation
The two accelerator pedal position signals disagree (safety-relevant).
O2 Sensor Signal Stuck Lean (Bank 1, Sensor 1)
The upstream oxygen sensor on bank 1 is stuck reading lean.
O2 Sensor Signal Stuck Rich (Bank 1, Sensor 1)
The upstream O2 sensor on bank 1 is stuck reading rich.
O2 Sensor Signal Stuck Lean (Bank 1, Sensor 2)
The downstream O2 sensor on bank 1 is stuck reading lean.
Diesel Particulate Filter - Soot Accumulation
The diesel particulate filter (DPF) is clogged with soot and not regenerating properly.
Lost Communication With ECM/PCM 'A'
A module lost communication with the engine computer over the car's data network.
Lost Communication With TCM
A module lost or received invalid communication over the car's data network.
Lost Communication With ABS Module
A module lost or received invalid communication over the car's data network.
Lost Communication With Body Control Module
A module lost or received invalid communication over the car's data network.
Lost Communication With Instrument Cluster
A module lost or received invalid communication over the car's data network.
Invalid Data Received From ECM/PCM
A module lost or received invalid communication over the car's data network.
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