Check Engine light on (Cat Efficency below threshold bank 1)

[Patonski]

Hi ,

I have this check engine warning light on a 2005 Corolla 1.4 vvti Petrol , I recently fitted a new catalyst and now have the (Cat Efficency below threshold bank 1) displayed as the fault on my diagnostic reader , though the reader will not allow me to reset the warning light, its one of those el cheapo (Maxi Scan MS 309 readers).

When I changed the Cat I never fitted a new oxygen sensor , would this be advisable ?

The old cat was replaced due to corrosion and leaking meaning the car could not be tested for emissions at the mot but the error light was not on ?

Any tips or advise would be much appreciated

Thanks

Patonski

[oldcodger]

You can clear the error code and check light by disconnecting the Battery for a few minutes, though that will probably put you into learning mode for the first 15 mins of running.

There is a long article on Cats in this months Car Mechanics magazine and it mentions about checking where and what you bought  as there are lots of fake/poor quality ones out there, UK law now states that they should only be a selling approved cats with the  E mark stamped on them, though expect the forgers will soon copy that !

Same with your sensor, if you get a new one, lots of poor ones out there than can give you more trouble than they are worth, so always get a good  make.

[Patonski]

7 hours ago, oldcodger said:

You can clear the error code and check light by disconnecting the battery for a few minutes, though that will probably put you into learning mode for the first 15 mins of running.

There is a long article on Cats in this months Car Mechanics magazine and it mentions about checking where and what you bought  as there are lots of fake/poor quality ones out there, UK law now states that they should only be a selling approved cats with the  E mark stamped on them, though expect the forgers will soon copy that !

Same with your sensor, if you get a new one, lots of poor ones out there than can give you more trouble than they are worth, so always get a good  make.

Hi ,

Thanks for replying , the cat I bought was a type approved CAT , I am pretty sure its the right quality as it was from a reputable trader on eBay , plus the car went threw the MOT with no emissions problems ,

Regarding disconnecting the Battery - When I initially changed over the CAT the check engine light was on , then after working on the car one night I left the interior light on and drained the Battery, when I recharged the Battery the light was off , then when I took the car for the mot I probably did about 30-40 miles in total that day , and the light remained off , it was only after I sold the car to a friend who drove it home about 10 miles  , parked up and next time he drove it the check engine light was on ?

So after considering all that I am not sure if disconnecting the battery completely would remove the light permanently but ill certainly give it a go and thanks for the advise ,

Would a high quality diagnostic machine be able to pin point the fault to either sensor ?

The Cat I bought link below 

 http://www.ebay.co.uk/itm/BM91604H-Catalytic-Converter-TOYOTA-COROLLA-1-6i-16v-VVTi-Hatchback-c-n-SB-o/282625390602?fits=Car+Make%3AToyota|Model%3ACorolla&hash=item41cdc9380a:g:CTsAAOSwSDZZoRgI

[T-Sport Novice]

The Battery trick will work but as you say, it came back on after a little while, it will get quicker at coming on after a batt reset the more you do it, I found anyway, had checn engine and TRC lights on, on my T-sport due to a dodgy backbox/cat. 

This is the problem with selling to a friend, I hope you manage to find a fix them. 

[oldcodger]

Am not an engine electronics guru, but as far as I know disconnecting the Battery clears the error code memory, which also turns off the check light.

If the light comes on when power is restored, or some time after, it means a new error has been sensed, recorded to memory and the check light turned on.

As that article I mentioned, on the cat there should be a long string of numbers stamped into the metalwork of the cat and in amongst them should be a much larger capital E  that signifies its the approved type.

Is you code reader coming up with the same error code each time after clearing  things with the Battery disconnect,   what is the actual code ?

Would have thought the simplest way to check things is to either swap out the sensor / s  ( could result in damaging things, do not try and clean them , results in more damage)  or just ask your local garage to do an emissions test which might show if the cat is working ok  ?

Be aware that the ecu might be changing the fuel mix to compensate for the error code  , which might throw things off during an emissions test ..??

[Patonski]

Hi

The code is P0420

The CAT is working fine as it passed the test , though as you say this error might be affecting the fuel mix so its possible it might not now pass a test with this error on.

I have not actually tried the Battery fix yet but my friend was planning to try and get the light reset at a local garage that'll do it for a tenner , if this doesn't fix it hopefully the guy will tell him which sensor it is , then ill just buy it and replace the sensor for him.

All I have done so far is read the code but my reader will not allow me to reset the code so its still displayed

It is a shame when these things happen when selling to a friend , makes me feel a bit guilty but I believe the car I sold him is still a decent motor for its age , with new mot , 3 new tyres, wipers , front discs and pads plus nearly all brake pipes done and a new catalyst fitted.

It would be nice to get this error cleared for my friend.

[oldcodger]

Have sent you an info sheet by PM,

Nope, couldn't load it in a pm, so its here,  will delete it later once you have seen it.

 

 

[Patonski]

looking at the trouble shooting guide you would say its most likely to be a Sensor gone , unless I have been unlucky and the CAT I fitted is faulty ? Though as it sailed through the emissions test at MOT that seems unlikely.

Thanks for posting the guide , ill update when we get a resolution for the problem.