I don't recall having to replace one on a 140, but if you have documentation saying it's the left rear, then often it will be behind the rear bumper panel or above the wheelwell splash panel, not just simply "underneath" where the muffler is. You can also look for rubber hoses or steel or plastic lines running to some obscure, tucked away place. But it won't be inside the body sheetmetal, like inside the trunk or under a seat, it will be someplace where fumes won't get inside the car somehow.

Gilly

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