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Catalytic Converter


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Hi all,

What's the reason to "Catalytic Converter" warning light appears in dashboard?

What's the fix has to be done?

catalytic_converter.jpg

Thanks

Hi Uditha

Means , you have bad emission in the exhaust system

go for a good mechanic ,

may need to check and replace O2 sensor and some exhaust parts as needed

thanks

regards

sumith

Edited by Sumiya
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Isint the O2 sensor related to the air intake than exhaust???

I dont see why you'd have to analize how much O2 is present in the exhaust thats merely leaving the combustion chamber...

Hi Dilesh

i guess air intake and level will definitely have effect on exhaust, because what ever air intake should be burned with fuel and final output is exhaust isn't it ?

thanks

Regards

sumith

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Hi Dilesh

i guess air intake and level will definitely have effect on exhaust, because what ever air intake should be burned with fuel and final output is exhaust isn't it ?

thanks

egards

sumith

True, what goes in is what comes out... But if its the o2 sense thats messed up shouldnt the warning be for that rather than the Cat.Con? I personally dont have a car with either of these sensors/warnings, but it would seem more logical for the root cause's warning to go off rather than the final effect's warning..

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True, what goes in is what comes out... But if its the o2 sense thats messed up shouldnt the warning be for that rather than the Cat.Con? I personally dont have a car with either of these sensors/warnings, but it would seem more logical for the root cause's warning to go off rather than the final effect's warning..

Hi Dilesh

No O2 sensor sense(unburned fuel ratio) and give instructions to ECU to Lean in or Lean out air fuel mixture getting oxygen ratio

of the exhaust , if it doesn't functioning properly(not getting correct voltage depending on O2 ratio) you get bad emission that is indicated through dash

thanks

regards

sumith

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Hi all,

What's the reason to "Catalytic Converter" warning light appears in dashboard?

What's the fix has to be done?

catalytic_converter.jpg

Thanks

what's the make model of your vehicle? Does it has an EGR. It could be something like over heated exhaust manifold.

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what's the make model of your vehicle? Does it has an EGR. It could be something like over heated exhaust manifold.

Thanks all for replies,

hi harshan,

This is Nissan Presea CTII 1996

It has catalytic converter (Don't know it's because this is a Japan domestic car)

It indicates this warning light. Car bit bad in fuel economy. Is there any relationship among them? Or Presea by default bad in fuel?? :rolleyes:

Any specific reason or fix please?

BTW. Cat Converter is also not 100% good. As it opens to water n mud, bit week (Thing normally happened to silencer barral :( )

Thanks...

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BTW. Cat Converter is also not 100% good. As it opens to water n mud, bit week (Thing normally happened to silencer barral :( )

What do you mean by this ,how can Cat be exposed to water and mud?

Could be a bad O2 sensor or bad Cat converter

Check the live data on both (if there is 2) O2 sensors using a scanner, Mechanic should be able to determine what's wrong by looking at it

Edited by AL998
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you will have to get it checked by a garage that can read the error code.

Any place to get this done? (Other than agent)

The garage should be a place where all these instrument are available right?

Any good place to get this done?

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Thanks all for replies,

hi harshan,

This is Nissan Presea CTII 1996

It has catalytic converter (Don't know it's because this is a Japan domestic car)

It indicates this warning light. Car bit bad in fuel economy. Is there any relationship among them? Or Presea by default bad in fuel?? :rolleyes:

Any specific reason or fix please?

BTW. Cat Converter is also not 100% good. As it opens to water n mud, bit week (Thing normally happened to silencer barral :( )

Thanks...

if the cat is blocked, yes it could affect performance and hence fuel economy. Since it's a '96 car, chances are high that the cat is blocked. If you take it a generic mechanic he'll break the cat and take all ceramic parts out and that's about it. But with emission regulations are around and in the process of making them strict, I don't recommend it.

Try to find out a second hand cat from japanese junk yards in Delkanda. Failing which you might have to go with what I said earlier. Break the CAT. All that is if the CAT is blocked, creates excessive pressure in the exhaust manifold. Therefore more important to isolate the issue, whether it's due to blocked CAT or failed lambda sensor.

You might require to hook it up with a code reader, may be you should try agents in that sense, at least to diagnose the error exactly. If it's lambda sensor you can replace the sensor and be happy but this is more like excessive pressure on manifold due to blocked CAT but I'm not 100% certain.

Edited by harshansenadhir
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Isint the O2 sensor related to the air intake than exhaust???

I dont see why you'd have to analize how much O2 is present in the exhaust thats merely leaving the combustion chamber...

machang most cars have two O2 sensors....one on the intake and one in the exhaust...

i believe the exhaust one is there to actually measure whether the fuel has been burnt properly....higher O2 in the intake and high O2 in the exhausts means the fuel hasn't been burnt properly... I think they use O2 sensors to even check proper fuel burn cos there are no petrol sensors on anything as such to see whether a full burn has happened

i read my manual quite a bit in the past few days after getting the check engine light and that's what i came to understand about the whole thing...

in my case it happened to lead to an error 52 which was the knock sensor being faulty...

simply the connector had come off the sensor and once connected and the ecu re-set all was fine for me...

On some model of cars the second o2 sensor is in the cat instead of on the exhaust manifold... part of the emission control system so if the sensor is not working properly...you get bad fuel economy...

when my knock sensor was disconnected you could smell the petrol fumes near the exhaust.. and also it failed the smoke test.

once connected... all is back to normal...

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if the cat is blocked, yes it could affect performance and hence fuel economy. Since it's a '96 car, chances are high that the cat is blocked. ....................

Hat off for ur descriptive advice n appreciate ur technical explanation... So I would hve to get two sensors and catalytic converter itself checked right?

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machang most cars have two O2 sensors....one on the intake and one in the exhaust...

Exactly true.. I true read so..

But what I understood was 1 is located in "Exhaust manifold" and other 1 is near catalytic converter.

Both sends commands to ECU(Computer of the Car) to help it decided

how much air to be issued according to current situation..

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machang most cars have two O2 sensors....one on the intake and one in the exhaust...

Machan that is not right

Both o2 sensors locate in the exhaust ,one before the CAT and One after CAT ,I think you are mistaken about the AIR MASS SENSOR which is in the inlet side.

BTW

What CAT does is, Burning any unburned/partially burned fuel and reducing harmful gasses such as nitrogen oxide and carbon monoxide .It converts carbon monoxide in to co2 and water with the help of oxygen .And a similar procedure to nitrogen oxide as well

So to do all the above things CAT needs oxygen . By measuring the O2 levels before and after CAT , ECU can determine whether cat is doing a good job or not

So if you get a fault code saying there is something wrong with sensor 1 then it could be the sensor itself,wiring or some other problem in the engine.If you can test the live data on o2 sensor1 ,you should get good sin wave

But if the fault codes say its the 2nd sensor then you have to take CAT in to consideration as well .Because it can be a faulty sensor or sensor is measuring a wrong signal due to CAT is not doing its job . Then you have check for any blocked or broken CAT and any exhaust leaks.

Some O2 sensors have a preheating circuit , If something wrong with these preheating circuits then fault codes will clearly say what is wrong in which sensor ,

So best thing is to get the ECU scanned and then go forward according to the fault codes given

Hope this helps

Edited by AL998
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Any place to get this done? (Other than agent)

The garage should be a place where all these instrument are available right?

Any good place to get this done?

debug auto exclusive on hill street Dehiwela can do it.

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I get the same light on mine, but my guess is in my case it is coz mine's cat converter has been removed

Arh. U got it removed?

Hmm.. I heard that some do so.

Btw. Does this increased ur fuel economy or any significant change in fuel econ?

Can this be safely removed if not in good condition?

Doesn't this affect to emission test to fail?

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Arh. U got it removed?

Hmm.. I heard that some do so.

Btw. Does this increased ur fuel economy or any significant change in fuel econ?

Can this be safely removed if not in good condition?

Doesn't this affect to emission test to fail?

Yup. Umm fuel economy, yeah maybe it helped, but i don't really know, but it's a bit noisy. Yes, could be just removed afaik and replaced with a straight pipe, but am not sure what happens if you have a 2nd O2 sensor after the cat (sure could affect it's readings). Din't fail me when I got my emissions test 2 months back. But again I wouldn't recommend you polluting the air around you with toxic fumes and the noise :D

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That warning is for overheating cat. Main reason for overheating the cat is that the car running rich. The un-burnt fuel is burning up in the cat and causing it to overheat.

There could be many issues that can cause this but the main culprit could be your O2 sensor or the coolant temp sensor.

BTW. There are no O2 sensors on the intake AFAIK. The sensor on the intake is the air temp sensor.

Generally there will be two O2 sensors. One before and one after the cat. The one before is what you need to check and make sure that it's sending the proper signal to the ECU. Also check your coolant temperature sensor as if this sensor is bad, the ECU will think the engine is cold and add more fuel thus causing it to run rich. Running rich will kill your engine performance, create carbon issues and foul your O2 and eventually burn up your cat.

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Arh. U got it removed?

Hmm.. I heard that some do so.

Btw. Does this increased ur fuel economy or any significant change in fuel econ?

Can this be safely removed if not in good condition?

Doesn't this affect to emission test to fail?

Theoretically speaking , removing the CAT cannot increase your economy ,Probably it will decrease it.

It will reduce the back pressure and give a wrong reading to the rear lambda sensor therefore MIL light will be always on

Edited by AL998
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Removing your CAT will increase your power at the top end but you'll lose some torque down low. You will definitely fail your emission.

To address the MIL issue just run a .05v resistor on the back sensor signal wire.

Edited by Mani
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  • 10 years later...

Hi,

I also have a similar problem, P0420. A Mechanic advised to remove the Cat. But im a bit skeptical about his advice. 

Is there any recommendable workshop around Colombo to get it fixed properly?

 

Thanks 

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3 hours ago, Assan said:

Hi,

I also have a similar problem, P0420. A Mechanic advised to remove the Cat. But im a bit skeptical about his advice. 

Is there any recommendable workshop around Colombo to get it fixed properly?

 

Thanks 

No..don't delete the catalytic converter for a normal daily, run of the mill car. That is the maka baas way to go about it. It will effect your car's emissions and even performance (eg...the engine has less back pressure to perform optimally..or soemtimes the lack of pressure might show a slight bit of increase in fuel economy....either way after the delete you will have to program the car to work properly...now performace cars do get de-cat'd but that is also complemented with a whoe lot of other upgrades). Eitherway....it is not the best way to go about it as now the car actually emits more harmful gases with no fiteration. In Japan it is illegalto run without a cat converter...so all the race boys who have de-catted their cars have the old stock cat at home and fit it on before going for inspections or taking it to the dealershi for any work.

Did you check both sensors (the pre and post) ? You cannot repair a catalytic converter but I am sure you might be able to find a used one if your car is a common model. De cat it only as a very very last resort

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