Catalytic converters


I have a 2004 Mercury Grand Marquis with 160,000+ miles. Two of my four catalytic coverters are going bad. Factory replacement parts are $1800 without labor.

My car is in great shape. It uses no oil between my 5,000 mile oil changes.

Is there a cheaper alternative?


if by “factory replacement” you mean an oem part then start with aftermarket converters which should be a lot less.

there are also aftermarket “universal” cats that, as far as I know are usually fine. you might also comb the salvage yards but the potential problems with that are obvious (here is a great site:

if you’re not good at sorting it out yourself, find a good independent mechanic if you don’t have one and ask for their recommendation.


Get a price from an independent mechanic. You don’t necessarily need Ford parts. There are less expensive after market exhaust suppliers.


Simply because there is a check engine light code about the catalyst system, or catalytic converter, doesn’t mean you have to replace the catalytic converters. There are some ignorant and/or dishonest mechanics will tell you that the catalytic converters have to be changed, when they don’t.
A check engine trouble code, like P0420, doesn’t mean to “change the catalytic converters”. Here is a checklist for those mechanics who have forgotten (or, not) some of the things to check when there is a trouble code for catalyst system: