Engine management code P0420 Catalyst system efficeny below threshold bank.

  1. #1
    My Engine management light came on the dash on sunday after giving it a full foot of full bore.

    Ive got a x red vtr on 66k miles.

    My AA cover, coveres me on the engine management light i found out so gave them a call today.

    He plugged it in and the code came up as P0420 which means "Catalyst System Efficiency Below Threshold Bank".

    He said its either one of my 02 sensors thats just about had it or my cat has just about had it.

    He turned off the light and he said, if it comes back on then go to a garage and get them to check it out.

    Also is there a thread on ecu codes at all?

    Dean
  2. #2
    So what exactly do you need to know?
  3. #3
    just letting people know what the code is basically, just trying to put up info that maybe usefull to someone else.
    And to see if anyone else has had this problem and could say whats the best way to sort it out etc.
  4. #4
    Ah ok thought you were after some help on it, as far as im aware there isnt a thread for engine codes. i have got them all on my computer like but theres far to many to go through and post them up
  5. #5
    no probz dude, if the code pops up again ill change the sensors then go from there.

    Do the cheapest thing first
  6. #6
    Aye good idea, ive had one at work and was the second sensor so id check taht one first
  7. #7
    do you know how to tell a sensor is faulty at all?
  8. #8
    Yea, you need to check the voltage's that are comming from the sensor, will get you a wiring diagram and some simple instructions tomorrow from work.
  9. #9
    your a star man!
    Ive got n volt meter so thats ok.