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P0420 - Catalyst System Efficiency below Threshold


Twopiece
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Hi All,

My car's engine light suddenly went "on", and i checked that the error code is P0420 - Catalyst System Efficiency below Threshold.

Went to a workshop and they told me cos I never speed my car long enough, carbon built up at the exhaust pipe area, nothing can be done with it.  So they just cleared the engine light with their device, and that's all.  Then after a few weeks, the engine light turned on again.

May I know any of you has such experience before?  According to the workshop i went to, they say such thing is very common in those eco cars.  Not sure if it's true?

Hope to hear some advices from gurus here.

Thank you!

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What car are you driving? Does it come with a petrol particulate filter?

Now that most cars have direct fuel injection the exhaust produces more particulates (much like a diesel engine). To pass emission standard a particulate filter is added.

Have you get an opinion from the AD workshop? Please go ask them. You go to some outside workshop they cant do anything cos they do not have the specific factory diagnostic tool. They cant reset the ecu and get reading from the exhaust side oxygen sensor to get the job done. Sometimes the error code does not show you the big picture. For your case it could be a leak along the exhaust system...anywhere from the exhaust manifold, gasket, exhaust pipe joint, oxygen sensor, etc etc. Need an experience mechanic to find out. I dunno where you go to and what exactly they have told you. Wtf is an "eco car"? Ppl come up with their own funny terms. What "dual injection"? it confuses ppl who are ignorant even more.

Edited by Watwheels
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Oh... my car is a 10 year old Honda Fit... 

wa... it sounds more complicated than what the workshop has told me...

haha... ya the workshop told me mine is one of those "eco cars" that is supposed to be more eco friendly? I'm not sure.. and they said in order to prevent such error, I probably need to drive up to 100-120 km/hr, and run for a few hours, which means shld drive up to Msia from time to time...

Indeed sounded a bit ridiculous... but then once the workshop saw the error code on their device, they confidently told me it's a very common problem... so... 

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16 minutes ago, Twopiece said:

Oh... my car is a 10 year old Honda Fit... 

wa... it sounds more complicated than what the workshop has told me...

haha... ya the workshop told me mine is one of those "eco cars" that is supposed to be more eco friendly? I'm not sure.. and they said in order to prevent such error, I probably need to drive up to 100-120 km/hr, and run for a few hours, which means shld drive up to Msia from time to time...

Indeed sounded a bit ridiculous... but then once the workshop saw the error code on their device, they confidently told me it's a very common problem... so... 

https://www.700r4transmissionhq.com/p0420-honda-fit/

Does not sound ridiculous as Cat needs heat to work properly.

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P0420 code means that yr cat convertor is chocked with carbon. The quick solution is to pump in detergent via the O2 sensor opening and allow the cleaning agent to soak up the carbon. The next action is to start and rev up the engine to above 2500 rpm.

U3C.jpg

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U3C_opt.jpg

Edited by Yeobh
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Supercharged

my last car threw P0420 code in its last 2 years of life

I reckoned it's the O2 sensor 

I was cheapskate,  I bought a cheap OBDII scanner online, reset the code whenever it appears, the car marched on for another two years before I scrapped it, no change in FC, drives normally and passed inspection too 

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On 1/11/2021 at 1:08 AM, Phang said:

my last car threw P0420 code in its last 2 years of life

I reckoned it's the O2 sensor 

I was cheapskate,  I bought a cheap OBDII scanner online, reset the code whenever it appears, the car marched on for another two years before I scrapped it, no change in FC, drives normally and passed inspection too 

No one get CHEAPER than me, as I am THE LORD of ALL CHEAPO !!

Aiya, just remove the CEL bulb and CARRY ON !!

 

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On 8/30/2019 at 7:52 AM, Twopiece said:

Hi All,

My car's engine light suddenly went "on", and i checked that the error code is P0420 - Catalyst System Efficiency below Threshold.

Went to a workshop and they told me cos I never speed my car long enough, carbon built up at the exhaust pipe area, nothing can be done with it.  So they just cleared the engine light with their device, and that's all.  Then after a few weeks, the engine light turned on again.

May I know any of you has such experience before?  According to the workshop i went to, they say such thing is very common in those eco cars.  Not sure if it's true?

Hope to hear some advices from gurus here.

Thank you!

Oh  I know, the ECU determine the efficiency via the O2 sensors lor.  The ECU insert a Lean burn from time to time, to provide the oxygen needed to CHARGE UP the Catalytic Convertor.  There should be 2 O2 sensor called Pre-O2 (before the convertor) and Post-O2 lor.

The test passing criteria, Pre-O2 will report Lean and Post O2 should report lean no later than 15ms or so lor.

As O2 sensor aged, the response time will slow lor, hence, causing the test to flag lor. It could be POST O2 failing and PRE O2 is "OK".

Generally, you should change O2 sensors every 150~200kkm.

Of course, your CAT could have aged or poisoned (Lead, SiO2, Di something simi sulphide etc..) 

Start with the cheaper way like removing the CEL light, or you cannot tahan Acceleration Hesitation or High Fuel Consumption than change O2 lor, if change O2 still like that, then change CAT lor OR <ADV> as a Teacher giving up driving to part with this NICE HONDA FIT lor .....

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On 1/22/2021 at 12:12 AM, Apple-Tree said:

No one get CHEAPER than me, as I am THE LORD of ALL CHEAPO !!

Aiya, just remove the CEL bulb and CARRY ON !!

 

Are you serious on removing the CEL bulb, or are you just ignorant of the consequence. Have you ever know the cpu going to  limb mode

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2 hours ago, Yeobh said:

Are you serious on removing the CEL bulb, or are you just ignorant of the consequence. Have you ever know the cpu going to  limb mode

Yup ...... I am serious about.  Usually, Emission Control Failure are secondary, you can confirm if it is a primary or secondary by looking at the CEL lor.

Secondary means more or less MINOR Failure while Primary means MAJOR Failure lor.

For Emission Control failure the CEL light up solid which means a minor lor.  It is when CEL is BLINKING, THAT IS SERIOUS lor.

 

Of course, there are exception lor, LIKE Ad-Blue run low,  that is major, you did not spend enough.  TOP UP or the CAR go Limping lor.....

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