Bad Miss
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Joined: May 2011
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Well I thought I was out of the woods. Thr truck was and is still running fine and the gas mileage even got better by about 2 mpg. All of a sudden after nearly two weeks, I get another CEL. This time it's a 420 code saying the catalyst system efficiency is below threshold on bank 1. Does this mean the cat is shot or is there anything else that could cause this?
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Joined: Apr 2011
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Stuck injector, and now cat trouble
Wow, Rotten luck........ If you have the ability to hook up a scanner to the truck, look at the data stream and watch your O2 sensors for bank 1 there will be two for each side. The first one "O211" should be switching from low to high voltage or from rich to lean quickly, while the second one the one after the cat, should switch very slowly. "O212" when the cat has been damaged or melted by too much fuel burning in the exhaust the ecm sees the second O2 sensor switching too fast compaired to the frist one. That is how it knows to tell you that your cats are bad.
You only have two or three choices, replace the cat - install a module to "lie" to the ecm about the exhaust, or just live with it and hope the cat is not stopped up enough to hurt your performance.
Good luck to ya. OH, by the way. don't buy your new cat from the dealer. Have a good muffler shop install one for you.
You only have two or three choices, replace the cat - install a module to "lie" to the ecm about the exhaust, or just live with it and hope the cat is not stopped up enough to hurt your performance.
Good luck to ya. OH, by the way. don't buy your new cat from the dealer. Have a good muffler shop install one for you.
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Wow, Rotten luck........ If you have the ability to hook up a scanner to the truck, look at the data stream and watch your O2 sensors for bank 1 there will be two for each side. The first one "O211" should be switching from low to high voltage or from rich to lean quickly, while the second one the one after the cat, should switch very slowly. "O212" when the cat has been damaged or melted by too much fuel burning in the exhaust the ecm sees the second O2 sensor switching too fast compaired to the frist one. That is how it knows to tell you that your cats are bad.
You only have two or three choices, replace the cat - install a module to "lie" to the ecm about the exhaust, or just live with it and hope the cat is not stopped up enough to hurt your performance.
Good luck to ya. OH, by the way. don't buy your new cat from the dealer. Have a good muffler shop install one for you.
You only have two or three choices, replace the cat - install a module to "lie" to the ecm about the exhaust, or just live with it and hope the cat is not stopped up enough to hurt your performance.
Good luck to ya. OH, by the way. don't buy your new cat from the dealer. Have a good muffler shop install one for you.
If it is the cat, it SHOULD still be under warranty. I never buy from the dealer unless thats the last resort. I've only had to take a vehicle to the dealer three times in my life, and that's over 40 year's of driving.
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Joined: Apr 2011
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DTC codes
Well I have a Snap-on vantage scanner. How many miles have you driven with a pending code? If the ecm is seeing a problem it should set the check engine light after a couple of drive cycles. If your light is not on after about 40 miles and a couple of warm-ups, you may have had that code pending from bruning the excess gas out of the cat after the repair.
You can see the voltage change with a good meter, but it is not high voltage, its millivoltage to a couple of volts. To tell if the cat is bad you have to compare the switching speed of the first sensor to the second. It is much easier to see with a scanner. If your still having trouble it might be worth your time and money to have someone connect a scanner to it for you.
You can see the voltage change with a good meter, but it is not high voltage, its millivoltage to a couple of volts. To tell if the cat is bad you have to compare the switching speed of the first sensor to the second. It is much easier to see with a scanner. If your still having trouble it might be worth your time and money to have someone connect a scanner to it for you.
Senior User
Joined: Apr 2011
Posts: 289
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From: Aurora Co
Jim, I always move a suspect coil to a different location to see if it changes the misfire location before replacing. I would suggest not only changing your oil as others have said, but also get the injection and induction system cleaned. This will prevent a lot of injection and other drive-ability problems. Glad to see you figured it out.
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