Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Trouble Code (DTC) Identification
1998 Lexus SC 300SECTION Diagnostic Trouble Code (DTC) Identification
DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION
| DTC | Description | Probable Cause | ||||
|---|---|---|---|---|---|---|
| P0100 (1) | Mass Airflow (MAF) Sensor Circuit Malfunction | Open/Short Circuit, MAF Sensor Or ECM | ||||
| P0101 (1) | Mass Airflow (MAF) Circuit Range/Performance Fault | MAF Sensor | ||||
| P0110 | Intake Air Temperature (IAT) Sensor Circuit | Open/Short Circuit, IAT Sensor Or ECM | ||||
| P0115 | Engine Coolant Temperature (ECT) Sensor Circuit Fault | Open/Short Circuit, ECT Sensor Or ECM | ||||
| P0116 (1) | ECT Sensor Circuit Range/Performance Fault | ECT Sensor Or Cooling System | ||||
| P0120 | Throttle Position (TP) Sensor Malfunction | Open/Short Circuit, TP Sensor Or ECM | ||||
| P0121 (1) | Throttle Position (TP) Sensor Circuit Range/Performance | TP Sensor | ||||
| P0125 | Insufficient Coolant Temperature For Closed Loop | Fuel System, Injection, Ignition System, Exhaust Gas Leakage, Open/Short HO2S Circuit Or HO2S | ||||
| P0130 (1) | (2) Heated Oxygen Sensor Circuit Malfunction (Bank 1, Sensor 1) | HO2S Or Fuel Trim Malfunction | ||||
| P0133 (1) | (2) Heated Oxygen Sensor Circuit Slow Response (Bank 1, Sensor 1) | HO2S | ||||
| P0135 (1) | (2) Heated Oxygen Sensor Heater Circuit Malfunction (Bank 1, Sensor 1) | Open/Short In Heater Circuit, HO2S Or ECM | ||||
| P0136 (1) | (2) Heated Oxygen Sensor Circuit Malfunction (Bank 1, Sensor 2) | HO2S | ||||
| P0141 (1) | (2) Heated Oxygen Sensor Heater Circuit Malfunction (Bank 1, Sensor 2) | Open/Short In Heater Circuit, HO2S Or ECM | ||||
| P0150 (1) | (2) Heated Oxygen Sensor Circuit Malfunction (Bank 2, Sensor 1) | HO2S Or Fuel Trim Malfunction | ||||
| P0153 (1) | (2) Heated Oxygen Sensor Circuit Slow Response (Bank 2, Sensor 1) | HO2S | ||||
| P0155 (1) | (2) Heated Oxygen Sensor Heater Circuit Malfunction (Bank 2, Sensor 1) | Open/Short In Heater Circuit, HO2S Or ECM | ||||
| P0156 (1) | (2) Heated Oxygen Sensor Circuit Malfunction (Bank 2, Sensor 2) | HO2S | ||||
| P0161 (1) | (2) Heated Oxygen Sensor Heater Circuit Malfunction (Bank 2, Sensor 2) | Open/Short In Heater Circuit, HO2S Or ECM | ||||
| P0171 (1) | System Too Lean (Fuel Trim) | Air Hose, Incorrect Fuel Pressure, Injector Blockage, HO2S, MAF Sensor, ECT Sensor Or Exhaust Gas leakage | ||||
| P0172 (1) | System Too Rich (Fuel Trim) | Incorrect Fuel Pressure, Injector Leak Or Blockage, HO2S, MAF Sensor, ECT Sensor Or Exhaust Gas Leakage | ||||
| P0300 | Random Misfire Detected | Ignition, Injector, Incorrect Fuel, Pressure, Compression, Valve Clearance, Valve Timing, MAF Sensor, ECT Sensor, Open/Short Circuit, Loose Connector Or ECM | ||||
| P0301 (1) | Cylinder No. 1 Misfire Detected | Ignition, Injector, Incorrect Fuel, Pressure, Compression, Valve Clearance, Valve Timing, MAF Sensor, ECT Sensor, Open/Short Circuit, Loose Connector Or ECM | ||||
| P0302 (1) | Cylinder No. 2 Misfire Detected | Ignition, Injector, Incorrect Fuel, Pressure, Compression, Valve Clearance, Valve Timing, MAF Sensor, ECT Sensor, Open/Short Circuit, Loose Connector Or ECM | ||||
| P0303 (1) | Cylinder No. 3 Misfire Detected | Ignition, Injector, Incorrect Fuel, Pressure, Compression, Valve Clearance, Valve Timing, MAF Sensor, ECT Sensor, Open/Short Circuit, Loose Connector Or ECM | ||||
| P0304 (1) | Cylinder No. 4 Misfire Detected | Ignition, Injector, Incorrect Fuel, Pressure, Compression, Valve Clearance, Valve Timing, MAF Sensor, ECT Sensor, Open/Short Circuit, Loose Connector Or ECM | ||||
| P0305 (1) | Cylinder No. 5 Misfire Detected | Ignition, Injector, Incorrect Fuel, Pressure, Compression, Valve Clearance, Valve Timing, MAF Sensor, ECT Sensor, Open/Short Circuit, Loose Connector Or ECM | ||||
| P0306 (1) | Cylinder No. 6 Misfire Detected | Ignition, Injector, Incorrect Fuel, Pressure, Compression, Valve Clearance, Valve Timing, MAF Sensor, ECT Sensor, Open/Short Circuit, Loose Connector Or ECM | ||||
| P0325 | Knock Sensor No. 1 Circuit Malfunction | Open/Short Circuit, Loose Sensor Or ECM | ||||
| P0330 | Knock Sensor No. 2 Circuit Malfunction | Open/Short Circuit, Loose Sensor Or ECM | ||||
| P0335 (1) | Crankshaft Position (CKP) Sensor Circuit Malfunction | Open/Short Circuit, CKP Sensor, Starter Or ECM | ||||
| P0340 (1) | Camshaft Position (CMP) Sensor Circuit Malfunction | Open/Short Circuit, CMP Sensor, Starter Or ECM | ||||
| P0420 (1) | Catalyst System Efficiency Below Threshold | Exhaust Gas Leakage, Catalytic Converter, Oxygen Sensor Or Circuit | ||||
| P0430 (1) | Catalyst System Efficiency Below Threshold | Exhaust Gas Leakage, Catalytic Converter, Oxygen Sensor Or Circuit | ||||
| P0440 (1) | EVAP System Malfunction | Vapor Pressure Sensor Or Circuit, Charcoal Canister, Gas Cap, Fuel Tank Or Faulty Vacuum Circuit | ||||
| P0441 (1) | Incorrect EVAP Purge Flow | Open/Short EVAP VSV Circuit, Vapor Pressure Sensor Or Circuit, Charcoal Canister Or Faulty Vacuum Circuit | ||||
| P0446 (1) | EVAP Vent Control Malfunction | Open/Short EVAP VSV Circuit, Vapor Pressure Sensor Or Circuit, Charcoal Canister Or Faulty Vacuum Circuit | ||||
| P0450 | EVAP Pressure Sensor Malfunction | Open/Short Vapor Pressure Sensor Circuit, Vapor Pressure Sensor Or ECM | ||||
| P0451 | EVAP Pressure Sensor Range/Performance | Open/Short Vapor Pressure Sensor Circuit, Vapor Pressure Sensor Or ECM | ||||
| P0500 (1) | Vehicle Speed Sensor Malfunction | Vehicle Speed Sensor Or Circuit, VSS Or ECM | ||||
| P0505 (1) | Idle Control System Malfunction | Electric Throttle Control System Or Loose Intake Air Hose | ||||
| P1120 | Accelerator Pedal Position (APP) Sensor Circuit Malfunction | Open/Short Circuit, APP Sensor Or ECM | ||||
| P1121 | Accelerator Pedal Position (APP) Sensor Range/Performance | APP Sensor Or ECM | ||||
| P1125 | Throttle Control Motor Circuit Fault | Open/Short Circuit, Throttle Control Motor Or ECM | ||||
| P1126 | Magnetic Clutch Circuit Fault | Open/Short Circuit, Magnetic Clutch Or ECM | ||||
| P1127 | Electronic Throttle Control System (ETCS) Fault | Open ETCS Power Circuit Or ECM | ||||
| P1128 | Throttle Control Motor Lock Fault | Throttle Control Motor, Throttle Body Or ECM | ||||
| P1129 | Electronic Throttle Control System (ETCS) Fault | ETCS Or ECM | ||||
| P1300 | Ignitor Circuit Malfunction | Ignitor Circuit To ECM, Ignitor, Coil/Igniter Or ECM | ||||
| P1335 | Crankshaft Position (CKP) Sensor Circuit | Open/Short CKP Sensor Circuit, CKP Sensor Or ECM | ||||
| P1349 | Variable Valve Timing (VVT) System | Valve Timing, Oil Control Valve, VVT Controller Or ECM | ||||
| P1520 (1) | Stoplight Switch Signal Malfunction | Short Circuit, Stoplight Switch Or ECM | ||||
| P1600 | ECM BATT Malfunction | ECM Power Source Circuit Or ECM | ||||
| P1633 | ECM Malfunction | ECM | ||||
| P1656 | Oil Control Valve (OCV) Circuit Fault | Open/Short OCV Circuit, OCV Or ECM | ||||
| P1780 (1) | Park/Neutral Position Switch Malfunction | Park/Neutral Position Switch/Circuit Or ECM | ||||
|
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RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.