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.
1995 Lexus LS 400FACTORY OEM SERVICE PROCEDURE
Engine Controls - Tests W/Codes - OBD-II
- Introduction
- Self-Diagnostic System
- Scan Tester Problems
- ECM Location
- Diagnostic Testing
- Notes
- Code P0100: Mass Airflow (MAF) Sensor Circuit
- Code P0101: Mass Airflow (MAF) Sensor Circuit Range/Performance Problem
- Code P0110: Intake Air Temperature (IAT) Sensor Circuit
- Code P0115: Engine Coolant Temperature (ECT) Sensor Circuit
- Code P0116: Engine Coolant Temperature (ECT) Sensor Circuit Range/Performance Problem
- Code P0120: Throttle Position (TP) Sensor Circuit Malfunction
- Code P0121: Throttle Position (TP) Sensor Circuit Range/Performance Problem
- Code P0125: Insufficient Coolant Temperature For Closed Loop Fuel Control
- Code P0130: Heated Oxygen Sensor Fault (Bank No. 1, Sensor No. 1) Code P0150, Heated Oxygen Sensor Fault (Bank No. 2, Sensor No. 1)
- Code P0133: Heated Oxygen Sensor (Bank No. 1, Sensor No. 1) Circuit Slow Response Code P0153, Heated Oxygen Sensor (Bank No. 2, Sensor No. 1) Circuit Slow Response
- Code P0135: Heated Oxygen Sensor Circuit (Bank No. 1 Sensor No. 1) Code P0141, Heated Oxygen Sensor Circuit (Bank No. 1, Sensor No. 2) Code P0155, Heated Oxygen Sensor Circuit (Bank No. 2, Sensor No. 1) Code P0161, Heated Oxygen Sensor Circuit (Bank No. 2, Sensor No. 2)
- Code P0136: Heated Oxygen Sensor Circuit (Bank No. 1, Sensor No. 2) Code P0156, Heated Oxygen Sensor Circuit (Bank No. 2, Sensor No. 2)
- Code P0170: Fuel Trim Malfunction
- Code P0300: Random Misfire Detected
- Codes P0301-P0308: Cylinder No. 1-8 Misfire Detected
- Codes P0325 & P0330: Knock Sensors No. 1 & 2 Circuit
- Code P0335 Or P1335: Crankshaft Position (CKP) Sensor Circuit
- Code P0336: Crankshaft Position (CKP) Sensor Circuit Range/Performance
- Code P0401: Insufficient Exhaust Gas RECIRCULATION (EGR) Flow Detected
- Code P0402: Excessive EGR Flow Detected
- Code P0403: EGR Circuit Malfunction
- Code P0420 & P0430: Catalyst System Efficiency Below Threshold
- Code P0441: Incorrect EVAP Purge Flow
- Code P0500: Vehicle Speed Sensor (VSS) Malfunction
- Code P0505: Idle Control System Malfunction
- Code P0510: Closed Throttle Position (CTP) Switch Malfunction
- Codes P1100: Barometric Pressure (BARO) Sensor Circuit Malfunction
- Code P1200: Fuel Pump Relay Circuit Malfunction
- Code P1300 & P1305: IGNITOR Circuit Malfunction
- Code P1400: Sub-Throttle Position (Sub-TP) Sensor Malfunction
- Code P1401: Sub-Throttle Position (Sub-TP) Sensor Circuit Range/Performance Problem
- Code P1500: Starter Signal Circuit Malfunction
- Code P1600: ECM Batt Malfunction
- Codes P1605: Knock Control ECM Malfunction
- Codes P1780: Park/Neutral Position Switch Malfunction
- Summary
- Connector Identification
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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