Check Engine Light MIL (Malfunction Indicator Lamp) Code 420. The Catalytic Converter is below the efficiency threshold. Best case scenario; the Downstream Oxygen Sensor has malfunctioned and needs to be replaced. Worst-case scenario; the Catalytic Converter needs to be replaced. On 4 cylinder Toyota's as well as other imports, this is a very inexpensive repair if you are will to do a little shopping and place a few phone calls.
Unlike other cars where the Catalytic converter is a flange (bolted on) part, Toyota four cylinder vehicles have their converters welded on their pipes. Various vendors provide aftermarket converts where the old converter can be cut off with a Sawzall, the new converter fitted on the existing pipe and then use exhaust clamps to keep it on. From personal experience, the clamps just don't work. The thickness of the new converter's pipe won't yield enough to create a leak-free fitting. Moreover, the pipes have a tendency to flex where they meet the catalyst pipe that it joins. The only solution is to weld the new converter to the existing exhaust system pipes.
After performing an internet search, a new catalyst was found for around $70. The pipe diameter on both the input and output ends of the converter was 2 inches; standard on most 4 cylinder Toyota vehicles. Next step; find a muffler shop to install it. Most reputable shops shouldn't charge over $75. The shop I use have consistently charged me $40 for 15 minutes of installation time. If they will not accept a converter that you are providing, keep moving (i.e keep shopping).
This article will describe what a typical Muffler Repair Shop will do to replace a catalytic converter.
Place Car on Lift and Cut off the Old Catalytic Converter
After placing the car on the lift, the technician will use a Sawzall to cut off the old Catalytic Converter.
Fit the New Converter on the Exhaust Pipes
- In some cases, the converter pipes might require flaring (expanding in diameter size).
- In some cases, an adapter pipe must be used if the overall length of the converter is too short.
Weld the Input and Output Ends of the Converter
- Most muffler shops use a MIG welder. They are easy to use and produce nice looking welds. I have been to other shops where the welding was sloppy and over-penetrated the pipe (that is it produced so much heat that the weld burned through the pipe it was welding on).
Start the Car and Check for any exhaust leaks
That is all there is to it. $70 for a new Catalyst ... $40 for installation.