Warm Up Catalist Insufficent In Bank 1 P0421

Fazmi Khan

Asked by Nov 29, 2015 at 10:27 PM about the 2006 Mitsubishi Lancer SE

Question type: Maintenance & Repair

Hi, im looking to purchase a used 2006 Mitsubishi lancer es automatic w/
182k on the odometer., the car looks great in and out.. price is $2600, but it's
service engine light is on, the owner said when he diagnosis it's
giving the  P0421 code which is Warm up catalist insufficent in bank 1. do you
think it's worth buying it, can i fixed it by going to a mechanic shop.

2 Answers


Well you know for sure that it is going to have to have at least one pre catalyst and the sensor as well, a good exhaust shop should be able to do this for you somewhere around 300 bucks maybe less. The price is good if everything else checks ok. Personally I never have liked Mitsubishi products, they have always seemed underpowered and overpriced on the parts, then there is the reliablity, just not that great. But as always the choice is yours, just do a little research on what you are looking at and go from there. HTH


Mitsubishi is a troublesome vehicle to most owners, but a cat coming on line "late" is usually dying from contamination from either running very rich (prolonged missing cylinder(s) and/or ignoring a CEL .... or from and engine that burns oil and wasted the cat. Mitsubishi was one of the first companies to build cats with "wire explosion" coatings that could not handle minor contamination of their catalyst beds. Hence, when other manufacturers found they could save $$$s by the same wire explosion coatings, then lube oils had to be reconfigured to "LE" oils that removed critically needed lubrication additives. In general..... LE oils cause a lot of untoward wear to older engine designs. There's always the possibility that the cat was changed for a used one, since a new or rebuilt one for the BIG THREE "M" cars (Mercedes-Mitsubishi-Mazda--- that charge exorbitant prices for their parts) was too expensive for someone to replace prior to selling their car. In my book, look for another car.

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