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johnkoehler1

Auxiliary heater malfunction on Mercedes SL

My 2001 Mercedes SL with a gasoline engine has developed a quirk The auxiliary heater refuses to engage The diagnostic system revealed an error stored in the error memory pertaining to the auxiliary heater Could this be the glow plug issue Is the temperature sensor playing tricks Or is the heater core itself compromised The ventilation system seems to be functioning adequately otherwise, and I haven't noticed any issues with the primary heat control Before I resign myself to a potentially costly repair I thought I'd seek advice Any thoughts, experiences, or suggestions

Summary of the thread

A 2001 Mercedes SL owner is experiencing an issue with the auxiliary heater not engaging, with a diagnostic error related to the heater. Possible causes include a faulty glow plug, a malfunctioning temperature sensor, or a compromised heater core. A suggestion to check the wiring harness for loose connections or damaged wires is made, and it is confirmed that the problem was indeed a defective glow plug, which was resolved by a professional mechanic.

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4 comment(s)

davidherrmann17

Sounds frustrating I had a similar issue with my SL The parking heater wouldn't kick on, and it turned out to be a faulty glow plug as you suspected Did you check the wiring harness leading to the auxiliary heater Sometimes a loose connection or damaged wire can mimic a defective glow plug Is the heater core warm when the engine reaches operating temperature

johnkoehler1 (community.author)

An intriguing suggestion Checking the wiring harness is something I had not yet considered When you experienced this similar issue, did the diagnostic system specifically flag the glow plug, or were there other seemingly unrelated error codes present And about the heater core, are you suggesting feeling the temperature of the heater core directly How easy is it to access

davidherrmann17

The diagnostic system was pretty specific about the glow plug on mine It could be a hassle to get to, so I brought it to the workshop They were able to confirm the problem quickly If you're not comfortable poking around under the hood, that might be your best bet

johnkoehler1 (community.author)

Ah, a definitive answer Thank you Your experience has emboldened me to face the music and seek professional assistance I shall entrust my SL to the capable hands of a trusted mechanic As it turns out, the fault indeed lay with a defective glow plug, just as we suspected I am now 440€ poorer, but at least the auxiliary heater is purring contentedly once more Your insights were invaluable in guiding me towards the correct diagnosis I am most grateful

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MERCEDES

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SL