1994 Mercedes-Benz S420 Repair and Maintenance

A guide to problems, costs, maintenance and repair for your 1994 Mercedes-Benz S420

1994 Mercedes-Benz S420 Problems

Faulty Mass Air Flow Sensor Causing Erratic Engine Operation and Poor Fuel Economy

A faulty mass air flow (MAF) sensor can cause erratic/rough engine operation and fuel economy issues. Since this sensor measures the actual amount of air entering the motor, when it fails, the engine control module (ECM) takes the wrong information and delivers incorrect volumes of fuel to the cylinders.

Insulation Degrades on Engine Wiring Harness and Leaves Conductors Exposed

The engine wiring can degrade because the insulating material falls off leaving the bare wire exposed. This can cause many problems depending on which wires are exposed and what they touch.

Closing Assist/Door Lock Issues Due to Pneumatic System Problems

Problems with the pneumatic system can cause closing assist and door lock issues.

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1994 Mercedes-Benz S420 Reviews

the heater valve blowing warm air out of the vents and air condition works off and on. I was told if I by pass the heater valve Ill have good air condition but no heat until I replace the heater valve. rather have cold then heat right now. And I was told I can rebuild the heater valve, so 1, how do I bypass the heater valve and 2 is there a kit to rebuild the heater valve and where do I buy it?...
My asr light is,on what is the problem and cost
I like this car, it is a 1994 S420, I had it for 6 years the main problem was the transmition, I have to build it twice. It has some electrical and minor michanical problems like any other cars the window motor has to be replaced twice, the heater/AC fan stopped workig for no reason, the sun roof gets stuck sometimes, the seats had some movement problem. Driving is enjoyable, engine is super po...

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