Letters: Do both catalytic converters need to be replaced?

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Q: I was told that my 2002 Ford Focus needs a new catalytic converter because the engine doesn’t have much power and the fuel economy is bad. I’m also being told that this car has two catalytic converters, one up close to the engine and one farther away from the engine.

Do you know if both catalytic converters need to be replaced, or can I get by with replacing just one of them? – Ross, Gilberts

A: A clogged catalytic converter can certainly cause poor fuel economy and a lack of power, but what’s important is determining which converter is faulty and why it failed. Even though your car has two catalytic converters, it’s unlikely that both need to be replaced at the same time. The technician needs to figure out which one is bad and why it failed.

An engine that is misfiring or running poorly can cause premature failure of the catalytic converter. You certainly don’t want to spend the money to replace the faulty catalytic converter only to have the new one fail prematurely due to a poorly running engine. If the technician isn’t sure which catalytic converter is faulty, take your Focus to a repair facility that specializes in emissions and/or exhaust system repairs for another opinion.

Q: I’m thinking about trading in my 2009 Pontiac G5 to get a new MazdaSpeed3. The G5 is no longer covered by a warranty and I’m worried about that. From an economic standpoint, do you think it makes sense to trade in my G5 for the MazdaSpeed3? – Terry, Chicago

A: No, it doesn’t make good economic sense. You already took the hit on depreciation with the G5. If you trade it in for the Mazda, you’ll be taking another hit for depreciation with the Mazda.

If not having a warranty has you worried, consider purchasing an extended warranty policy for the G5. There are many companies out that that sell warranties. Some aren’t good, though. Just be sure to read all the fine print and understand what will or won’t be covered, and what the deductible will be.

However, if you’re not happy driving the G5 and you’ll be happier driving the Mazda, then do what makes you happy.

Q: I’m having trouble with the blower motor intermittently cutting out in my 2008 Cadillac STS4. It’s been to the dealer several times during the past eight months for this condition. They’ve replaced the blower motor and it still cuts out intermittently. The dealer can’t find anything else wrong. Do you know what might be causing this? Are there any service bulletins for this? – Tom, Chicago

A: I didn’t find any service bulletins. There could be something wrong with the wiring, the blower motor relay, the blower motor control module or the climate control module. To see if the blower motor relay could be the cause, try swapping the FRT BLWR relay with another relay, like the STRTR (starter) relay. If the relay is acting up intermittently, swapping it with the starter relay may affect starting, but that’s something you don’t operate continuously like the blower.

Questions for Ira Siegel? Call the Auto Advisor Hotline at (708) 633-6839 or e-mail ira.siegel.is@gmail.com. Siegel is an automotive instructor and an automotive service excellence-certified master auto technician.