Mercedes 450SL Problems

Updated February 21, 2017

Introduced in 1973, the Mercedes-Benz 450 Sport Light (SL) is a roadster manufactured by Mercedes.

Fast Idle

If your Mercedes 450SL idles fast when the engine is cold, a failed idle air control valve, which controls how much air enters the engine, may be at fault. Check the idle air control valve and valve wiring for indications of wear or damage and make any necessary replacements.

Reduced Engine Power

Lack of engine power at high speeds can result from a major vacuum leak in your Mercedes 450SL, which allows uncontrolled air into the engine, upsetting the air-fuel ratio in the combustion mixture. Check the vacuum hoses for signs of tears or wear and replace them as needed.

Instrument Panel Light

A Mercedes 450SL instrument panel that fails to light can be due to a blown fuse or failed dimmer switch. Check the fuse panel for any darkened fuses and replace them. If the panel fails to reactivate, check the dimmer switch in the instrument cluster for corrosion that can build up on the wires. Clean off the corrosion and flip the dimmer switch up and down a few times. If the switch still fails to operate, it must be replaced.

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