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P0421 Code on 2001 Mitsubishi Montero Sport: Is $3K Repair Price Reasonable?

Model: Mitsubishi Montero Sport Fault Code: P0421 Posted: 2007-06-15 10:28

My 2001 Mitsubishi Montero Sport has been showing the 'Service Engine Soon' light intermittently for several years. This time, it failed inspection because the light remains on. The dealer diagnosed a P0421 code, indicating that both Bank 1 and Bank 2 catalytic converters are not functioning properly during warm-up. They have quoted a repair cost of $3,000. I'm wondering if this price is reasonable, and whether there's a way to reduce the expense. Additionally, when searching online, most sources only reference Bank 1 in relation to P0421—does anyone know more about how Bank 2 might be involved or what alternatives exist for repair?

Related fault codes
P0421
Comments (5)
Anonymous 2007-06-15 11:34

Original equipment catalytic converters can be costly, and labor costs may push the total over $2,000. Most vehicles of this age don't come with extended warranties, so replacement is typically a full outlay.

Anonymous 2007-06-15 15:20

The factory warranty covers up to 80,000 miles—my vehicle has reached 83,000 miles. So, no coverage available for this issue.

Anonymous 2007-06-16 15:45

I'd request the dealer to split the cost: one party pays for parts and another covers labor. At my workplace, we offer this arrangement for loyal customers who maintain a good relationship with us.

Anonymous 2007-06-18 09:30

The dealer may recommend replacing both banks due to age-related degradation of the older converter. You could ask them to replace only the faulty bank first and schedule the second later. Also, consider visiting an independent mechanic—some offer lower rates than dealerships (though quality varies). Avoid choosing the cheapest option, as it might lead to poor workmanship or short-term fixes. Cost isn't always equal to value.

Anonymous 2007-09-09 13:59

lskcooper wrote: \nNo, warranty up to 80K miles - it has 83K . . . go figure!\nHey how's it going?\nI have a 2000 Montero Sport LS 4x4 with 75K miles and just received the same P0421 code. I'm curious—what did you do to fix it? Did you end up taking it back to the dealership? I definitely don't want to spend $3,000 on exhaust components. Thanks for any advice or tips!\nDiscover more\nCoil\nVehicle\nPlugs