# Engine lights on after changing catalytic converter



## Toyota auris (Oct 20, 2020)

Hi everyone. 
catalytic converter was stolen from Toyota Auris 2013 few months ago. I fit the third party parts and since then the engine lights is on on the dash board. 
Anyone who has or had the issue and how did they solved???


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## tohunt4me (Nov 23, 2015)

Toyota auris said:


> Hi everyone.
> catalytic converter was stolen from Toyota Auris 2013 few months ago. I fit the third party parts and since then the engine lights is on on the dash board.
> Anyone who has or had the issue and how did they solved???


Get computer reset/ reprogrammed.
Clean oxygen sensor/ or replace.


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## Daisey77 (Jan 13, 2016)

Do you have a code reader or know someone who does? The code will help you distinguish exactly what the issue is. It also will clear the code. Clearing the code won't fix the issue, if there is in fact one but if the car still has memory stored from previously, the computer could be getting conflicting information and may just need to be reset. If you don't have access to a code reader, pull the negative battery cable, give it a couple of minutes and reconnect. That'll clear the check engine light and you'll have to see if it comes back on.


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## Toyota auris (Oct 20, 2020)

Daisey77 said:


> Do you have a code reader or know someone who does? The code will help you distinguish exactly what the issue is. It also will clear the code. Clearing the code won't fix the issue, if there is in fact one but if the car still has memory stored from previously, the computer could be getting conflicting information and may just need to be reset. If you don't have access to a code reader, pull the negative battery cable, give it a couple of minutes and reconnect. That'll clear the check engine light and you'll have to see if it comes back on.


Thank you Daisy. 
My Mechanic tried those steps and the light is still on. I have been driving with the light for few months now. I need to sort it out.


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## ANT 7 (Oct 14, 2018)

Does the aftermarket cat have the internal core density of the OEM cat, or is it a high flow model ?

Some cheaper aftermarket cats and performance ones have fewer cells, thus they trigger the CEL. This is probably the issue.


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## Boca Ratman (Jun 6, 2018)

What code is it giving? 

A small piece of black electrical tape will fix it.


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## observer (Dec 11, 2014)

I just had the catalytic stolen out of my Prius.

I was told it could be replaced with an aftermarket for 650 bux but it may not pass smog.

The only other legal alternative is to replace it with an OEM catalytic.

Not sure what the requirements are in London.


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## kc ub'ing! (May 27, 2016)

Disconnect the battery for 5 minutes. That’ll reset the computer. Worth a shot. Worked for me!


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## Daisey77 (Jan 13, 2016)

Toyota auris said:


> Thank you Daisy.
> My Mechanic tried those steps and the light is still on. I have been driving with the light for few months now. I need to sort it out.


 do you know what code it gave the mechanic?


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## Terri Lee (Jun 23, 2016)

Forums 
Garage 
*Vehicles*


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## mbd (Aug 27, 2018)

CAT’S will be hit and miss with the E lights, even if you put OE.
Pay extra to pass inspection and put a tape to cover the E light and keep driving if you don’t feel any misfiring, lower mpg. You can try CAT cleaner on the old Cat, cost 25$ AutoZone.


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## Toyota auris (Oct 20, 2020)

My license on the car is due to renew and it will need to go through inspection by TFL. It need to be sorted.


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## 25rides7daysaweek (Nov 20, 2017)

Toyota auris said:


> My license on the car is due to renew and it will need to go through inspection by TFL. It need to be sorted.


Dont try to cover the light or bribe the dmv. You might disconnect the battery for 10 minutes. If the cat was the cause of the light to begin with it may go out.


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## Soldiering (Jan 21, 2019)

Two words for you. Third party.

That's your problem


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## Daisey77 (Jan 13, 2016)

Have you cleared the code at all? If not you need to do that to see how long it takes for it to come back on. You might be able to get it to clear long enough for you to get through inspection. I don't know what all your inspection involves but unless it's something pretty major , you might still be able to pass. The parameters programmed to trigger those lights can be pretty sensitive. So you might not be far enough outside the normal range to trigger an emissions failure. If you clear the code and light doesn't come on for a couple of days you might be good to pass, if you go right after clearing the code. 🤷‍♀️ 

Your mechanic ever give you the code that popped up? Do you know if in fact he did actually clear the code? The fact you said the light was still on makes me think he didn't even clear the code because it will go away for a short time regardless until it has time to measure everything again and sense something is out of whack to trigger the check engine light


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## TheDevilisaParttimer (Jan 2, 2019)

Take it to the dealer for a real diagnostic.


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## Amsoil Uber Connect (Jan 14, 2015)

Get yourself a FixD code reader, install app on phone. Now you know. 

It's saved me a few headaches.


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## Toyota auris (Oct 20, 2020)

So this is the code reader pointing the problem


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## tohunt4me (Nov 23, 2015)

Toyota auris said:


> So this is the code reader pointing the problem
> 
> View attachment 522005


Clean mass air flow with spray.
Clean throttle body.
Check for catalytic convertor clog

You have 1 or 2 cat. Units ?

Catalyst from 1st could be in exhaust blocking 2nd. Car could be in Limp mode due to exhaust obstruction.


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## Toyota auris (Oct 20, 2020)

I have one cat unit but as far as away know. It has two sensor. One attached to the cat and second one at front under the bonnet. I was thinking it might be the sensor. As when the cat was stolen those morons took the sensor as well. So the sensor is third party parts.


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## Daisey77 (Jan 13, 2016)

It's your EGR solenoid. Most likely it's bad or else something is causing it to stay open or stay closed . other possibilities are bad wiring or your PCM is failing. Most likely your 403 code is causing your 102 code though


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## Amsoil Uber Connect (Jan 14, 2015)

Did you try clearing the codes and trying again ?


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## observer (Dec 11, 2014)

Toyota auris said:


> I have one cat unit but as far as away know. It has two sensor. One attached to the cat and second one at front under the bonnet. I was thinking it might be the sensor. As when the cat was stolen those morons took the sensor as well. So the sensor is third party parts.


If they stole your cat they most likely stole your oxygen sensor.

Ask me how I know. &#129402;&#129402;&#129402;&#129402;

But whoever replaced your cat should have at least told you if it was missing.


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## Toyota auris (Oct 20, 2020)

observer said:


> If they stole your cat they most likely stole your oxygen sensor.
> 
> Ask me how I know. &#129402;&#129402;&#129402;&#129402;
> 
> But whoever replaced your cat should have at least told you if it was missing.


The sensor was missing and then mechanic attached the third party one.

They tried, but it didn't work. 
He does five or six cars every day, never experienced this type of problem before.
May be Auris is definitely different than prius, as most of the cars comes to him are prius. 


Amsoil Uber Connect said:


> Did you try clearing the codes and trying again ?


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## kingcorey321 (May 20, 2018)

ANT 7 said:


> Does the aftermarket cat have the internal core density of the OEM cat, or is it a high flow model ?
> 
> Some cheaper aftermarket cats and performance ones have fewer cells, thus they trigger the CEL. This is probably the issue.


Yes indeed this will cause that p0420 code. 
Here is a trick it will slow or stop the engine light from coming back on.
Its a old race car trick lol . 
On the bottom o2 sensor screw this in . Then put your o2 sensor into it . o2 sensor that is after the cat
See we old schoolers bypass the cat that robs the engine of 10 % of its horsepower . 
https://www.autozone.com/ignition-t...zbXE6z1JVlD3V6IzorRoCj3UQAvD_BwE&gclsrc=aw.dsIf this does not fix it give us the code. It may be a code you do not need to worry about and you can drive your car with out issues .
Again fuel savings might be affected if the light is on depending .


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