Dear Tom and Ray:

My "check engine" light illuminated a few weeks after a Jiffy Lube oil change. I took my 2008 Subaru Impreza in to the dealer, and they pulled a shop rag out of my car (it was blocking two-thirds of the air intake). Upon request, Jiffy Lube agreed to pay for the dealer's services (I am still awaiting reimbursement). Several weeks later, both my air/fuel sensor and my mass air sensor failed prematurely. The dealer agreed that these are related to the rag, and helped me draft a letter to Jiffy Lube requesting full reimbursement for $750. Is there anything else I can or should do, besides NEVER going to this Jiffy Lube for an oil change again?

-- Lily

TOM: Well, unfortunately, these things do happen, Lily. I've left rags in some unusual places myself.

RAY: The most embarrassing places are the ones where his wife ends up finding them!

TOM: Usually a rag left in the air-filter housing won't do any damage. But I'm guessing that in your case, it ended up getting sucked into the air intake and substantially blocking it. That caused your engine to run rich (i.e., too much fuel, not enough air).

RAY: And that would instantly cause the sensors to start working to correct the situation. My guess is that the sensors got overworked and overheated, and that's what caused them to fail, turning on the check-engine light.

TOM: So what else might fail? Well, if the sensors were unable to keep up, and the car was allowed to run rich for an extended period of time, the catalytic converters might be damaged.

RAY: Those can run into serious money. But the good news is that your catalytic converters are warranted, by federal law, for eight years or 80,000 miles. And if you bought the car in a state that has adopted California emissions standards, your converters are covered for 15 years or 150,000 miles! So it's more likely to be your dealer's problem than yours if they fail prematurely. I'd let the dealer decide whether to address the converter issue with Jiffy Lube.

TOM: It might be a hard sell, anyway. Unless your dealer takes the converters down, inspects them and certifies that the honeycombs have already started to melt from overheating, I think you'll have a hard time turning Jiffy Lube upside down and shaking two new converters out of them.

RAY: But they certainly should reimburse you for the sensors. And you are well within your rights never to patronize that particular Jiffy Lube again.

TOM: Yeah, my brother no longer goes to the ear, nose and throat doctor who was clearing out his nose hairs one day and left a gas-powered weed whacker hanging out of each nostril.