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.
1998 Lexus ES 300FACTORY OEM SERVICE PROCEDURE
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 (2) | Insufficient Coolant Temperature For Closed Loop | Open/Short Circuit, HO2S or ECM | ||||||||
| P0125 (3) | Insufficient Coolant Temperature For Closed Loop | Open/Short Circuit, A/F Sensor or ECM | ||||||||
| P0130 (1)(2) | (4) Heated Oxygen Sensor Circuit Malfunction (Bank 1, Sensor 1) | HO2S Or Fuel Trim Malfunction | ||||||||
| P0133 (1) | (4) Heated Oxygen Sensor Circuit Slow Response (Bank 1, Sensor 1) | HO2S | ||||||||
| P0135 (1) | (4) Heated Oxygen Sensor Heater Circuit Malfunction (Bank 1, Sensor 1) | Open/Short In Heater Circuit, HO2S Or ECM | ||||||||
| P0136 (1) | (4) Heated Oxygen Sensor Circuit Malfunction (Bank 1, Sensor 2) | HO2S | ||||||||
| P0141 (1) | (4) Heated Oxygen Sensor Heater Circuit Malfunction (Bank 1, Sensor 2) | Open/Short In Heater Circuit, HO2S Or ECM | ||||||||
| P0150 (1)(2) | (4) Heated Oxygen Sensor Circuit Malfunction (Bank 2, Sensor 1) | HO2S Or Fuel Trim Malfunction | ||||||||
| P0153 (1) | (4) Heated Oxygen Sensor Circuit Slow Response (Bank 2, Sensor 1) | HO2S | ||||||||
| P0155 (1) | (4) Heated Oxygen Sensor Heater Circuit Malfunction (Bank 2, Sensor 1) | 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 | ||||||||
| P0401 (1) | Insufficient EGR Flow Detected | EGR Valve Stuck Closed, Open/Short EGR Gas Temperature Sensor Circuit, EGR Gas Temperature Sensor, EGR VSV Open Circuit, EGR VSV, Vacuum Control Valve, Vacuum Hose Disconnected Or Blocked, Or ECM | ||||||||
| P0402 (1) | Excessive EGR Flow Detected | EGR Valve Stuck Open, Open/Short EGR Valve Position Sensor Circuit, EGR Valve Position Sensor, EGR VSV Open, EGR VSV Short Circuit Or ECM | ||||||||
| P0420 (1)(2) | Catalyst System Efficiency Below Threshold | Catalytic Converter, Oxygen Sensor Or Circuit | ||||||||
| P0420 (1)(3) | Catalyst System Efficiency Below Threshold | Catalytic Converter, Oxygen Sensor Or Circuit, A/F 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, Instrument Cluster, ECM or ABS ECU | ||||||||
| P0505 (1) | Idle Control System Malfunction | IAC Valve Or Circuit, Open/Short A/C Signal Circuit Or Loose Air Intake Hose | ||||||||
| P1130 (1)(3) | Air/Fuel Ratio Sensor (AFS) Circuit Range/Performance | Open/Short A/F Circuit, AFS Or ECM | ||||||||
| P1133 (1) | Air/Fuel Ratio Sensor (AFS) Response Malfunction | AFS | ||||||||
| P1135 (1) | Air/Fuel Ratio Sensor (AFS) Heater Circuit Malfunction | Open/Short AFS Heater Circuit, AFS Or ECM | ||||||||
| P1150 (1)(3) | Air/Fuel Ratio Sensor (AFS) Circuit Range/Performance | Open/Short AFS Heater Circuit, AFS Or ECM | ||||||||
| P1153 (1) | Air/Fuel Ratio Sensor (AFS) Response Malfunction | AFS | ||||||||
| P1155 (1) | Air/Fuel Ratio Sensor (AFS) Heater Circuit Malfunction | Open/Short AFS Heater Circuit, AFS Heater 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 | ||||||||
| P1410 (1) | EGR Valve Position Sensor Circuit Malfunction | Open/Short EGR Valve Position Sensor Circuit, EGR Valve Position Sensor Or ECM | ||||||||
| P1411 (1) | EGR Valve Position Sensor Circuit Range/Performance | EGR Valve Position Sensor | ||||||||
| P1520 (1) | Stoplight Switch Signal Malfunction | Short Circuit, Stoplight Switch Or ECM | ||||||||
| P1600 | ECM BATT Malfunction | ECM Power Source Circuit Or ECM | ||||||||
| P1780 (1) | Park/Neutral Position Switch Malfunction | Park/Neutral Position Switch/Circuit Or ECM | ||||||||
|
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Factory Service Tools
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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.
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