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Old 04-29-2018, 03:17 PM
 
1,879 posts, read 629,688 times
Reputation: 2699

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Disconnect your battery cable for a minute and reconnect. This might temporarily keep the light off. I have a car that I eliminated the cats on, and occasionally, the light pops on. I remove the cable and it is off for a week or two.
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Old 04-29-2018, 04:47 PM
 
Location: Southern California
971 posts, read 1,025,054 times
Reputation: 2305
Quote:
Originally Posted by elias9193 View Post
Go to a muffler shop but stay away from Midas they are not the most trustworthy or reliable.
This is an understatement.
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Old 04-29-2018, 06:42 PM
 
Location: Log "cabin" west of Bangor
5,508 posts, read 6,472,067 times
Reputation: 9475
Usually, the O2 sensors fail first, a good code reader should be able to tell you if there is an open/shorted circuit, high/low voltage or if the sensor is not coming up to temp. Other info in the computer may assist in diagnosing the 'rich' condition if there is one. Insufficient air flow can cause a rich condition.

The engine requires a particular air/fuel mixture. If there is not enough air or too much fuel flow, then it is running 'rich'. If there is too much air or not enough fuel, then it will be running 'lean'.

You can't just automatically assume that the cat is bad. Far too many halfassed 'techs' just guess at this stuff and start replacing parts in the hope that they will hit on the part that is bad, instead of doing a proper diagnosis and determining where the actual failure is.

Don't go to Midas. Don't go to Meineke either, they are just as bad. Either take it to the appropriate dealer, or a good independent.
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Old 04-29-2018, 08:01 PM
 
Location: Travelers Rest S.C.
126 posts, read 139,774 times
Reputation: 166
Quote:
Originally Posted by TrapperL View Post
The p0128 means that the temperature of the engine is not getting up to normal. It can be a variety of things that causes it but the thermostat is the most common. But, it can also be an engine running too rich. If the gas mileage is lower than it should be, I would suspect it to be a rich condition causing the problem. The P0420 means that the catalytic converter is not performing function in that the O2 sensor at the front of the converter is reading almost the same thing as the O2 sensor behind the converter. This can be as a result of the engine exhaust temps are just not hot enough, read rich condition, to make the converter work correctly. Most normally, when a converter fails, it's due to another problem that caused it to fail. You need to have a shop fix it correctly or expect failure again. I would be looking for a high flow type converter if it needs replacement. Usually they are considerably cheaper than a factory replacement. Depending on the engine/car, a new converter can be as little as a hundred bucks. Shop around for prices as one is just as good as the next one.
Correct answer.
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Old 05-03-2018, 07:24 AM
 
208 posts, read 101,350 times
Reputation: 478
A friend from work had his dad who is a master mechanic inspect it for me and he said I can continue to drive it without any serious issues and didn't see a need to get it fixed. Not sure if I should take his advice with a grain of salt though and can't afford to shell at a large amount of $ right now yet at the same time this is my main source of transit.
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Old 05-03-2018, 10:44 AM
 
8,281 posts, read 6,126,292 times
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P0128 as others have said is MOST LIKELY a stuck open thermostat.

If it were me, I would just replace it, assuming that you're at or over 100k miles since it's been replaced, or if it hasn't ever been replaced. At that point, while yes, you're loading up the parts cannon.. It's your vehicle and it's entirely justifiable to replace the thermostat even if it isn't bad. Totally unacceptable to do this if you were a shop and it was a customer car, but.. Fine for your own. Probably got an 85% chance of it fixing the problem, and if it doesn't.. No great loss.


P0420.. You need something to read OBD-II statuses to fix. Now, technically.. You could start the vehicle up and measure temps before and after the Cat, but.. I find that only mildly reliable. You should have a higher temp coming out of the cat vs going in. And don't forget that pending on vehicle, you might have TWO cats. I haven't seen one, but I hear there are some with more than 2 now?

The problem here is that the P0420 can be set by so many things. As others have mentioned, a bad/slow O2 sensor can do it, and the O2 sensor MAY not throw a code on itself. You really need something that will do more than read codes. You need to monitor the O2 sensor readings to see what they are outputting and a code reader isn't going to cut it. For this.. I'd say find a shop that will run tests and not immediately say "You need a cat".. Ask them to explain WHY you need a cat.. If they just say you have a cat code.. Go somewhere else. They should be able to tell you why they arrived at the diagnosis of a bad cat. An exhaust leak can throw that code.

Now.. if the cat is rattling when at idle and when you hit the gas the rattle goes away.. yeah.. You need a cat. The catalyst has come loose inside the converter.
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Old 11-18-2018, 12:23 PM
 
1,190 posts, read 938,527 times
Reputation: 1968
Reviving this thread as I have a related question and I've always received good responses from many of you in this forum.

I had repair work/inspection/routine maintenance done last week on my 2012 Nissan rogue. Drive off and an hour later the check engine light was on. Today I just left the same garage for a check of that issue. Guy says it might just be a hiccup from the work I had done last week and he can reset the light. If it doesn't come back on, great. If it does come back on, it's most likely the catalytic converter and that can be a very expensive job. So of course I opted for resetting the light, and so far the light hasn't come back on. In the meantime, I just checked cost of a new converter and am seeing prices between $104 - 189. Even with labor, why am I seeing average replacement costs of $1000? Does it really take that long to fix?

Thanks in advance for your replies!
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Old 11-18-2018, 02:17 PM
 
2,214 posts, read 507,030 times
Reputation: 1548
Quote:
Originally Posted by bridgerider View Post
Reviving this thread as I have a related question and I've always received good responses from many of you in this forum.

I had repair work/inspection/routine maintenance done last week on my 2012 Nissan rogue. Drive off and an hour later the check engine light was on. Today I just left the same garage for a check of that issue. Guy says it might just be a hiccup from the work I had done last week and he can reset the light. If it doesn't come back on, great. If it does come back on, it's most likely the catalytic converter and that can be a very expensive job. So of course I opted for resetting the light, and so far the light hasn't come back on. In the meantime, I just checked cost of a new converter and am seeing prices between $104 - 189. Even with labor, why am I seeing average replacement costs of $1000? Does it really take that long to fix?

Thanks in advance for your replies!

If the way you have to change a headlight on a Murano is any indicator, yes.
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Old 11-18-2018, 03:30 PM
 
1,190 posts, read 938,527 times
Reputation: 1968
Quote:
Originally Posted by Creamer1 View Post
If the way you have to change a headlight on a Murano is any indicator, yes.
LOL...thanks. (I think!)
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Old 11-18-2018, 06:34 PM
 
Location: Brawndo-Thirst-Mutilator-Nation
15,448 posts, read 15,401,410 times
Reputation: 11212
I would write down those codes, clear them and see if those exact same codes come back.....go from there.

It sounds like the cat is throwing a code, that is possibly connected to the 0128.....maybe not a bad cat.
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