Lexus GS Parking Heater Issue

Greetings. The symptoms you describe, namely the inability to activate the parking heater coupled with a stored error related to the auxiliary heater, strongly suggest a fault within the auxiliary heating system itself. The auxiliary heater, often used in modern vehicles to supplement the main heating system, especially in colder climates or during engine warm-up, relies on several components. Before suggesting more involved diagnostics, can you confirm if any other climate control functions are behaving erratically? Does the main heating system operate normally when the engine is running? Confirming these observations would be beneficial.

Thanks for the quick response! To answer your questions, the regular heat works perfectly fine when the engine is running. It's just the parking heater that's completely dead. Also, everything else related to the climate control seems normal – AC, blower, all good. Could it still be something simple, or am I looking at a major repair bill?

Given that the primary heating functions are operational, and the fault is isolated to the auxiliary heater, the probability of a defective glow plug is elevated. Glow plugs are used to preheat the combustion chamber within the auxiliary heater. Failure of a glow plug will prevent the auxiliary heater from igniting, thus disabling the parking heater function. While a comprehensive diagnostic procedure is recommended, replacement of the glow plug is a logical first step. Based on typical repair costs for this model and issue, expect an expenditure in the region of 440€. However, it is always advisable to seek a professional assessment to preclude any unforeseen complications.

Wow, thanks a bunch for the info! Glow plug, huh? I never would have guessed. I'll take it to a shop and have them check it out. Your explanation makes perfect sense, and at least now I have a better idea of what to expect. Turns out it WAS the glow plug, as you suspected. Got it replaced for 430€ and now the parking heater is working again! Thanks for the help!