Hi guys,After filling up at Tesco the other night the light has come on and code reads catalyst efficiency below threshold - P0420. I get this code every 3 or 4 months if I have to mix fuel i.e. I normally fill up at Morrisons (unleaded) and car runs fine, performs well and no lights etc... (UK 2001 Bugeye).If I put Tesco unleaded in or Shell the light will come on the next day or so.. If I clear it, then it will probably stay off. Car passed MOT in Dec and CATs were working fine (or at least good enough to pass) so im not sure if this is CATs being 12 years old, dodgy o2 sensor or the mix of petrol with not being super or Tesco 99 etcExhaust system is std at the mo, no map etc.... I am looking to fit the Ninja 100 cell downpipe and afterburner centre and vortex rear box from scoobyworld in the next month or so.What Im asking is how can I stop the light coming on as I assume I will need to either edit the ecu or install some kind of bypass resistor when i fit the new downpipe? I have access to a Tactrix cable and laptop so i could install some software and tweak something if someone could advise?Prior to fitting a new exhaust system is there an interim fix via openecu etc?TaMike

 

Sounds like your CAT is getting tired. Like you say, it's good enough for MOT pass but it's failing the OBD checks done when driving.

If you have the Tactrix kit you can upload your current ECU calibration, turn off the P0420 and reflash it back to the ECU. This will stop P0420 from re-appearing.

You may find that your new Ninja 100 cell CAT work's well enough to not trigger P0420 but I would suggest turning it off anyway. The ECU will need some map changes to suit the new downpipe so could turn off P0420 whilst it is being remapped.

 

Yes, thats what im after for now, disabling that code so light isnt triggered for now. Does anyone know which opensource software is best and easiet to use for this? I assume there is a backup function to use first before then making changes and reflashing?

 

I use ECUflash for uploading, editing and reflashing. You can use it to upload the ROM from your ECU and you can then save that as a backup. Edit it and save again then reflash it.