Weird P0420 error and behavior

nikkon

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Hi all,
after driving the car with the tune and aftermarket spell parts in the description I got the P0420. One important fact : the car did 1500 km in the last 2 years and because I live in the Netherlands, the motorway speed is 100 km/h
I used my OBD2 diagnosis tool and I got the P0420 error code. As the intercooler and downpipe are bigger I was thinking maybe the tune is broken. However, I did both a bottle of Liqui Moly Benzine Systeemonderhoud 300ml and I decided to drive a long way ( Amsterdam to Aosta - Italy) after 3-400 km the error message disappeared. I derived the car in Italy for 3 days in a city and the error appears again. Now on my way back to Amsterdam after 600km the error goes away.
Now, I wander is the tune?, the catalytic converter or the slow drive in town that caused the issue? I fear the air/gas mix is not working well when the error is on.
thanks in advance
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gtman

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nikkon

nikkon

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gtman

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You still should add your tuned car to the thread I linked (if you want to help the community).
 

Two Step Performance

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Thanks for the reply. My tune was done by ATM-Chiptuning I don’t have ktuner or no hondata.
In this case, you will need to return to your tuner to see if they can disable the error code for you.
 


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nikkon

nikkon

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Posted as well on the recommended thread.
 
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nikkon

nikkon

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Hi all,
I am reopening this thread as I have some new data:
I've talked to the tuner: they can't fix it.
I've been to the dealer a few times and they just deleted the error code.
Now I've drove the car more in the last period and I've observed the following:
Without the check system working on if have short rides ( 100-150 km) and i drive (as required by law) with 100km/h max in the six gear the error shows up. Faster when the temperature was lower outside.
If I drive log ranges (200-500 km) with the error on, during the drive it disappears (it happens only after a stop/start engine)
My conclusion - could be a stupid thing - is that the sonde measuring the gas temperature in the downpipe is not reaching the right temperature or the temperature inside is not high enough.
When I changed the intercooler and the downpipe, the shield that was attached on the OEM downpipe was not mounted on the Wagner one. I was thinking this might cause the temperatur problem .
What do you think?
 

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You have an aftermarket downpipe, it is labeled as euro6 but will still be less efficient at it's job than the stock one, when the secondary O2 sensor sees the downpipe being less efficient over time the ECU will trigger the "catalyst efficiency" error code. Your tuner probably cant disable the code in the tune by law or they dont have the tools on their software to do it. Best you can try is a defouler or switch to ktuner.
 

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What Kytos said. The catalyst efficiency code from the aftermarket downpipe can be avoided with a defouler plug that moves the sensor farther from the exhaust stream. When doing this it's also possible to get a different error, sensor slow response, as it's not picking up enough exhaust now. The good news is these codes don't effect anything at all. No metrics or performance is effected. It's just a nucance that warning light comes on to tell you your oem cat is bad (or is different).
 
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nikkon

nikkon

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Just ordered one.
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