I HANVE A 2005 MITSUBISHI GALANT GTS. THE CAR COMES WITH 2 CATALYTIC CONVERTORS. MY ENGINE LIGHT CAME ON, AND I TOOK IT TO GET A DIAGNOSTIC, AND WAS TOLD I NEEDED TO REPLACE BOTH CATALYTIC CONVERTORS. I TOOK IT TO AUTOZONE, AND GOT A PRINT-OUT OF THE CODES THAT CAME UP, AND THE TWO CODES THAT DID, BOTH RELATE TO THE OXYGEN SENSORS AND THE CAT ON BANK 2 ONLY. I NEED HELP FIGURING OUT WHICH CATALYTIC CONVERTOR REPRESENTS ''BANK 2.''
You have a V6 engine, bank one is the row of cylinders on the passenger (right) side, bank two is the row of cylinders on the drivers side (left). Your codes indicate an inefficiency in the cat on the left side but this could be due to a bad O2 sensor or an engine that is out of tune and overloading the cat. This car seems too new to have a bad cat. I would change the plugs and the O2 sensor after the cat before going any further. The reason I say the O2 after the cat, it's the one that is critical in sensing cat efficiency. What is the mileage?
The O2 before the cat regulates the air fuel ratio that the engine burns and the O2 after the cat checks for complete oxidation within the cat. The whole system falls apart though if the engine is missing, even a small imperceptible amount. A miss introduces oxygen into the exhaust stream and confuses the computer. It is critical that you have good spark plugs. For the life of me, I've never understood why manufacturers have started recommending 100,000 mi spark plug changes. I guess it is so they can market the car as "maintenance free". Even with platinum plugs, there is too much at risk, catalytic converters are far more expensive than spark plugs, let's say every 40,000 mi!
It is possible that your cat has been damaged and will need to be replaced, but you would be crazy to spend the money on new one without replacing the spark plugs as this is what no doubt would have damaged it in the first place. What I've suggested is a shot, but a good one that would have to done regardless. If you really want, you could do the front (sensor 1) O2 as well but they are expensive and I'm trying to be conservative.
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CODE NUMBERS WERE P0431 AND P0432
I HAVE ABOUT 81,000 MILES ON THE CAR. WHAT DOES THE O2 SENSOR BEFORE THE CAT DO?
OK, UNDERSTOOD. I ACTUALLY BOUGHT SOME BOSCH PLATINUM SPARK PLUGS A LITTLE WHILE AGO, BECAUSE I WAS GONNA TRY AND DO THE TUNE-UP MYSELF. PROBLEM IS 3 SPARK PLUGS ARE RIGHT IN FRONT, WHEN YOU POP THE HOOD. THE WAY THE ENGINE IS DESIGNED THOUGH, THE OTHER THREE ARE REALLY DIFFICULT TO GET TO; I THINK I WOULD'VE HAD TO TAKE OFF A BLOCK IN ORDER TO REACH THEM......I JUST GOT A PRICE OF ABOUT $200 TO GET THEM CHANGED, SO I'LL DO THAT, AND HAVE THE O2 SENSOR CHANGED ALSO, AS YOU RECOMMENDED. HOPEFULLY THE CAT IS FINE, BECAUSE I THINK IT'S THE ONE DIRECTLY CONNECTED TO MY EXHAUST MANIFOLD, AND FROM WHAT I'M TOLD, THE DEALER CHARGES $800-900 FOR THAT CAT! THANKS FOR YOUR HELP DAVES, YOU ARE THE MAN!
What were the code numbers ?
Catalytic convertor red hot.
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