The AAC is an $800 part at list price. I negotiated a deal with my independent shop to sell it to me for $600 since we were taking a chance on it not actually being my problem. I essentially bought it from him at his cost. the AAC is also simple to swap out, but I don't know if it needed any programming to activate it.

The ETS sensor was about $50.

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02 S500
92 500SL
92 400E (Sold)
87 300E (Sold)
83 300D Turbo (Sold)
75 300D (Sold)
74 240D (Sold after 20 years)