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.
1990 Mercedes Benz 300CEFACTORY OEM SERVICE PROCEDURE
Engine Controls - Tests W/Codes
- Introduction
- Self-Diagnostic System
- Entering Self-Diagnostics
- Retrieving Codes (CALIF Vehicles)
- Retrieving Codes (Federal Vehicles)
- Code And Component
- Testing With On-Off Ratio Tester
- Trouble Shooting
- Clearing Codes
- Test Step Charts
- Impulse Display Code Charts
- Display 1: No System Malfunction,
- Display 2: Full Load Contact
- Display 3: Coolant Temperature Sensor
- Display 4: Airflow Sensor Position Indicator
- Display 5: O2 Sensor
- Display 6: Not Used
- Display 7: TD - Signal
- Display 8: Altitude Correction Capsule
- Display 9: ELECTROHYDRAULIC Actuator
- Display 10: Idle Speed Contact
- Display 11: Not Used
- Display 12: EGR Temperature Sensor
- Summary
Factory Service Tools
Use the Manual With the Right Hardware
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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.