Hi guys! hoping somebody can help me with my issue. My Malfuntion indicator light came on while i was driving on the motorway doing about 70mph. I have got the car for well over a year now and its done 58000 miles and had its major service last august. Car has been completely fine no problems at all until this light came on.

I read into forums and manage to get a hold of an OBD-II scanner. Pulled up the codes and P0420 came up- catalyst system efficiency below threshold (bank 1)

Resetted the code, as my car has a de cat on it rather than a catalytic converter. Light didnt come back on again until i was once again driving on the motorway driving over 60mph seeems to trigger it. I took it into Honda and they diagnosed it as a catalytic failure. Honda was no help at all when i started mentioning o2 sensors as the car had a de cat fitted when i bought the car - (dealer never told me)

so my question is - is it ok to use aftermarket catalytic convertors? coz honda is quoting me £1400 for a cat convertor, and i can get one for £200.

Any one ever had a problem similiar to mine? like whenever you go over a certain speed limit it triggers the MIL?

any help will be appreciated - thanks

 

It's quite common to get that code when using a decat, what it's telling oyu is that the emissions after the cat are high, which they will be with no cat.

Most people use a spacer to take the secondary lambda sensor (one in the cat) out of the exhaust flow a bit, and that stops the CEL coming on.

£200 is a lot for a second hand cat imo.

Either way, there is zero harm to the car so carry on driving it

 

Thanks for the reply! So any suggestions where I can get a cheaper cat? The one thing I don't understand is that the light comes on after 1 year of driving it with the Decat . Any suggestions for where I can get a cheaper car will be great, thanks again

 

Keep the decat and get the sensor spacer. Have you been passing MOTs with the decat on?

 

https://www.s2ki.com/forums/index.php?showtopic=848406

Or speak to GarageR about a new one.

Then bung your old one on eBay.

 

The car had it's mot back in november! And it actually failed on emissions! That was the first time I noticed that my car had a de cat fitted as the dude from the mot explained it to me, so I borrowed my mates cat and it passed!

I think Garyr de cat looks good if It will solve the problem coz it's pretty annoying and distracting having the light on all the time.

So will most garage fit the de cat for me even though it's illegal? Or is it legal?
And what are the prices for a sensor spacer? What's the best way to tackle this? New de cat pipe or a spacer? Thanks again for the great replies

 

If you speak to or PM GarageR as advised above you will receive answers to your questions...