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.
1991 Mercedes Benz 300CEFACTORY OEM SERVICE PROCEDURE
Engine Controls - System/Component Tests
- Introduction
- Engine Sensors & Switches
- Fuel Pump Relay (420SEL & 560 Series)
- OVERVOLTAGE Protection Relay
- Fuel Delivery System
- Fuel Control System
- After-Start Enrichment
- Altitude Correction Capsule (420SEL & 560 Series)
- Fuel Cut-Off DECEL Solenoid (190E 2.6L & 300 Series)
- Fuel Cut-Off DECEL Solenoid (420SEL & 560 Series)
- Full-Load Enrichment
- Lambda Control (CALIFORNIA)
- Lambda Control (Federal)
- Start Valve (190E 2.6L & 300 Series - Method A)
- Start Valve (190E 2.6L & 300 Series - Method B)
- Start Valve (420SEL & 560 Series)
- Idle Control System
- EZL Ignition System
- Emission Systems & Sub-Systems
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
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.