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 SC 400FACTORY OEM SERVICE PROCEDURE
Engine Performance DTCS
ENGINE PERFORMANCE DTCS
| OEM Code | Description |
|---|---|
| 12 | RPM SIGNAL CIRCUIT (NO. 1) |
| 13 | RPM SIGNAL CIRCUIT (NO. 2) |
| 14 | IGNITION SIGNAL (IGNITOR NO. 1) |
| 15 | IGNITION SIGNAL (IGNITOR NO. 2) |
| 16 | A/T CONTROL SIGNAL MALFUNCTION |
| 21 | MAIN O2 SENSOR SIGNAL LEFT OR RIGHT BANK |
| 22 | ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT |
| 24 | INTAKE AIR TEMPERATURE SENSOR CIRCUIT |
| 25 | AIR/FUEL RATIO MALFUNCTION (LEAN) |
| 26 | AIR/FUEL RATIO MALFUNCTION (RICH) |
| 27 | SUB-OXYGEN SENSOR CIRCUIT (LEFT BANK) |
| 28 | MAIN O2 SENSOR SIGNAL LEFT OR RIGHT BANK |
| 29 | SUB-OXYGEN SENSOR CIRCUIT (RIGHT BANK) |
| 31 | AIRFLOW METER CIRCUIT |
| 35 | BAROMETRIC PRESSURE SENSOR CIRCUIT |
| 41 | TPS SIGNAL & SUB-TPS SIGNAL |
| 42 | VEHICLE SPEED SENSOR (VSS) CIRCUIT |
| 43 | STARTER SIGNAL |
| 47 | TPS SIGNAL & SUB-TPS SIGNAL |
| 51 | SWITCH CONDITION SIGNAL |
| 52 | NO. 1 KNOCK SENSOR SIGNAL, KNOCK CONTROL SIGNAL & NO. 2 KNOCK SENSOR SIGNAL |
| 53 | NO. 1 KNOCK SENSOR SIGNAL, KNOCK CONTROL SIGNAL & NO. 2 KNOCK SENSOR SIGNAL |
| 55 | NO. 1 KNOCK SENSOR SIGNAL, KNOCK CONTROL SIGNAL & NO. 2 KNOCK SENSOR SIGNAL |
| 71 | EGR SYSTEM MALFUNCTION |
| 78 | FUEL PUMP CONTROL CIRCUIT |
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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