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Catalytic Converter needs to be replaced, Subaru WRX 2008

I got a code PO420 and my repair shop told me I need a new Cat. This is the parts list and prices they gave me for the work.

Front Cat Converter- $568
Rear Cat Converter --$670
Gasket Muffler------$9.77
Gasket x2----------$17.96
Exhaust Donut Gasket $20
Reary Oxygen Sensor–$159
Front Air Fuel Ratio Sensor $199

Total cost after tax and labor $2,026.

Does this sound/Look about right?
I appreciate any help/advice.

According to the diagram I found (attached), the downstream oxygen sensor is located on the inlet of the rear cat converter…which means the rear converter isn’t monitored. IMHO unless you have a flow problem the rear converter does not need to be changed.

Does the vehicle have more than 80,000 miles on it? Catalytic converters are covered under the emissions warranty for 8 years/80,000 miles.

The car has 100k on it. The last owner drove it quite a bit.

Is it worth getting the sensors replaced first to see if they are faulty and then replacing the Cats?

Time for a second opinion. I have seen to often the symptom is repaired but not the problem that caused it.

What is it a symptom of?

Absolutely replace all four oxygen sensors before you even think about replacing either cat. Check your owner’s manual, but it probably recommends replacing the oxygen sensors somewhere between 90k and 110k miles. When oxygen sensors get old and their response time gets slow, it is common that the first code that appears is “catalyst efficiency low” which is what you got. Your mechanic should know this, but he wants to sell you $2000 worth of parts.

Buy the oxygen sensors on line and replace them yourself. If the code returns (which I doubt) then think about catalysts. You won’t have wasted a penny and you will have already saved $100 over what a shop will charge you for the sensors. You can get Denso sensors on line for $250 for the pair, no sales tax and free shipping.

P.S. If it turns out that you do need new cats, those prices look about right. The only way to save money there is to pay a muffler shop to weld in generic cats, which might be fine, but I hesitate to suggest it.

PPS - the first line of my post said four oxygen sensors. My mistake. Your car has two, or more precisely, as you said, one air/fuel sensor and one oxygen sensor.

Funny, the cat was ok at 79k miles but failed at 100k. Such is life.

It’s funny, I drove my last vehicle 130k miles in 15 tyears and never had to reolace the Cat converter. The muffler was going bad tho.

@EllyEllis if you have no misfires, no oil consumption, no blown headgaskets, no leaking fuel injectors, etc. your catalytic converter can last a LONG time.