engine light...catalytic problems...
Thread Starter
Le Mans Master
Joined: May 2015
Posts: 5,187
Likes: 1,215
From: Las Vegas Nevada
engine light...catalytic problems...
Folks,
My 2008 base C6 with 101,000 miles on it is showing an engine light. I had Oreilly's check it out, and it came up "catalyst system below threshold, bank 1". My car has one converter on each side.
Is it likely the converter, or possibly a sensor? I am getting ready to put a z06 system on the car, so if it is the converter, I don't want to spend the money to fix that, as it will soon be replaced. If it is a sensor, it obviously needs to to be replaced. If it is a sensor, how do I know if it is the front or rear sensor?
I am assuming the "bank 1" is driver side...correct? Coincidentally, the driver side downpipe on the z06 system I will be installing needs a new converter, so that has to be taken care of before I do the switch.
So, any ideas on what might be the root cause?
My 2008 base C6 with 101,000 miles on it is showing an engine light. I had Oreilly's check it out, and it came up "catalyst system below threshold, bank 1". My car has one converter on each side.
Is it likely the converter, or possibly a sensor? I am getting ready to put a z06 system on the car, so if it is the converter, I don't want to spend the money to fix that, as it will soon be replaced. If it is a sensor, it obviously needs to to be replaced. If it is a sensor, how do I know if it is the front or rear sensor?
I am assuming the "bank 1" is driver side...correct? Coincidentally, the driver side downpipe on the z06 system I will be installing needs a new converter, so that has to be taken care of before I do the switch.
So, any ideas on what might be the root cause?
Last edited by buckmeister2; Apr 4, 2017 at 04:30 PM. Reason: left off some words
Burning Brakes
Joined: Oct 2015
Posts: 1,139
Likes: 108
From: Arlington Texas
More than likely it is the catalytic converter. I believe the oxygen sensors give a different code. To verify it is the cat you can unbolt the exhaust from the manifold on the drivers side. Start the motor and wait to see if the engine light goes out. Since you are getting into the exhaust this far you might as well replace the system with the ZO6 type. Magnaflow makes high flow cats for a resasonable price.
Drifting
Joined: Jul 2005
Posts: 1,625
Likes: 187
From: Austin TX
Could be either. You can wait until after you put the Z06 system on to see if that fixes it. Same thing happened to me right before I put my long tubes on. Since I was doing a header swap and my inspection was coming up, I paid a tuner $25 to "turn them off" to pass inspection.
Thread Starter
Le Mans Master
Joined: May 2015
Posts: 5,187
Likes: 1,215
From: Las Vegas Nevada
Could be either. You can wait until after you put the Z06 system on to see if that fixes it. Same thing happened to me right before I put my long tubes on. Since I was doing a header swap and my inspection was coming up, I paid a tuner $25 to "turn them off" to pass inspection.
Jim
Thread Starter
Le Mans Master
Joined: May 2015
Posts: 5,187
Likes: 1,215
From: Las Vegas Nevada
More than likely it is the catalytic converter. I believe the oxygen sensors give a different code. To verify it is the cat you can unbolt the exhaust from the manifold on the drivers side. Start the motor and wait to see if the engine light goes out. Since you are getting into the exhaust this far you might as well replace the system with the ZO6 type. Magnaflow makes high flow cats for a resasonable price.
Burning Brakes
Joined: Oct 2015
Posts: 1,139
Likes: 108
From: Arlington Texas
New cat welded to the ZO6 down pipe is the cheapest way to go. I'm pretty sure Magnaflow sells ZO6 down pipes with converters also. But since not many people are going to see it I'd just get the universal converters welded on. Recently my truck had a 3 inch Magnaflow cat start to rattle from the inside. The warranty just ran out at nine years old. For probably marketing reasons they only sold both sides at a time. I bought a new universal cat that was the same and had it welded on to the existing pipes for half the money.
Le Mans Master
Joined: Dec 2004
Posts: 5,488
Likes: 804
From: West coast CA
Is it likely the converter, or possibly a sensor? I am getting ready to put a z06 system on the car, so if it is the converter, I don't want to spend the money to fix that, as it will soon be replaced. If it is a sensor, it obviously needs to to be replaced. If it is a sensor, how do I know if it is the front or rear sensor?
Thread Starter
Le Mans Master
Joined: May 2015
Posts: 5,187
Likes: 1,215
From: Las Vegas Nevada
Thanks for your question, and reply.
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Thread Starter
Le Mans Master
Joined: May 2015
Posts: 5,187
Likes: 1,215
From: Las Vegas Nevada
New cat welded to the ZO6 down pipe is the cheapest way to go. I'm pretty sure Magnaflow sells ZO6 down pipes with converters also. But since not many people are going to see it I'd just get the universal converters welded on. Recently my truck had a 3 inch Magnaflow cat start to rattle from the inside. The warranty just ran out at nine years old. For probably marketing reasons they only sold both sides at a time. I bought a new universal cat that was the same and had it welded on to the existing pipes for half the money.
Yeah, I checked on the Magnaflow cat/pipe....$600!! I just bought two more manifolds and two downpipes w/good cats for half that much, so I am good to go.
Thread Starter
Le Mans Master
Joined: May 2015
Posts: 5,187
Likes: 1,215
From: Las Vegas Nevada
Could be either. You can wait until after you put the Z06 system on to see if that fixes it. Same thing happened to me right before I put my long tubes on. Since I was doing a header swap and my inspection was coming up, I paid a tuner $25 to "turn them off" to pass inspection.
Safety Car
Joined: Nov 2007
Posts: 4,433
Likes: 873
From: Bay Area CA
The full 3" Z06 exhaust is a better exhaust and will require a retune. The Z06 exhaust manifold is basically a shorty header with 4 individual pipes that meet at the collector. So, if more horsepower is your goal, go with the Z06 exhaust.
Last edited by Mike's LS3; Apr 5, 2017 at 02:16 AM.
Thread Starter
Le Mans Master
Joined: May 2015
Posts: 5,187
Likes: 1,215
From: Las Vegas Nevada
Thread Starter
Le Mans Master
Joined: May 2015
Posts: 5,187
Likes: 1,215
From: Las Vegas Nevada
There is a voluntary emissions recall (mandatory in CA) on 2008-09 models that replaces the original cats and add two more cats at the mid pipe. This is a free fix, but two more cats (total of 4) will be added.
The full 3" Z06 exhaust is a better exhaust and will require a retune. The Z06 exhaust manifold is basically a shorty header with 4 individual pipes that meet at the collector. So if more horsepower is your goal, go with the Z06 exhaust.
The full 3" Z06 exhaust is a better exhaust and will require a retune. The Z06 exhaust manifold is basically a shorty header with 4 individual pipes that meet at the collector. So if more horsepower is your goal, go with the Z06 exhaust.
Jim
Le Mans Master
Joined: Dec 2004
Posts: 5,488
Likes: 804
From: West coast CA
From the description it sounds like P0420 which happens when the signal from the downstream O2 sensor starts to look like the one from the upstream sensor, within some tolerance, suggesting an underperforming catalyst.
Graphing the live data from both sensors can give you a better picture but if the cat is bad you may want to look into why. A stock cat on a stock motor should last longer than 100K miles. Has your car been modified? Were there any other trouble codes set?
Safety Car
Joined: Nov 2007
Posts: 4,433
Likes: 873
From: Bay Area CA
Le Mans Master
Joined: Oct 2014
Posts: 8,667
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From: Atlanta GA
More than likely it is the catalytic converter. I believe the oxygen sensors give a different code. To verify it is the cat you can unbolt the exhaust from the manifold on the drivers side. Start the motor and wait to see if the engine light goes out.
If it's the sensor, it would be the rear (downstream) one.
Same thing happened to me right before I put my long tubes on. Since I was doing a header swap and my inspection was coming up, I paid a tuner $25 to "turn them off" to pass inspection.
And you cannot turn off the front sensors ...... not without a lot of work as you would have to run the car in open loop .
if you have to turn off the rear sensors on a stock system ... somethings wrong , like a blocked cat ... and that could cause trouble ....
Thread Starter
Le Mans Master
Joined: May 2015
Posts: 5,187
Likes: 1,215
From: Las Vegas Nevada
There's an underlying code there that isn't being presented by whatever scan tool they're using, then.
From the description it sounds like P0420 which happens when the signal from the downstream O2 sensor starts to look like the one from the upstream sensor, within some tolerance, suggesting an underperforming catalyst.
Graphing the live data from both sensors can give you a better picture but if the cat is bad you may want to look into why. A stock cat on a stock motor should last longer than 100K miles. Has your car been modified? Were there any other trouble codes set?
From the description it sounds like P0420 which happens when the signal from the downstream O2 sensor starts to look like the one from the upstream sensor, within some tolerance, suggesting an underperforming catalyst.
Graphing the live data from both sensors can give you a better picture but if the cat is bad you may want to look into why. A stock cat on a stock motor should last longer than 100K miles. Has your car been modified? Were there any other trouble codes set?
Bone stock, and no other trouble codes. The car spent it's first 100K in Kalifornia. They have a ton of fuel restrictions, some of which I have read are pretty hard on converters. I'm not concerned, as I will be doing the Z06 soon. If I still have a problem, we will tackle it at that time.
Thanks for the input.