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Ey up!

FYI - 2002 9n 1.2 12v AZQ

VAGCOM throws up ...

16804/P0420/001056 - Catalyst System; Bank 1: Efficiency Below Threshold

Ross-Tech suggest the below.

Possible Causes
Leakage in Intake and/or Exhaust System
Catalyst faulty
Oxygen Sensor(s) faulty
Oxygen Sensor(s) Control faulty

Possible Solutions
Check Intake and Exhaust System for Leaks
Check Catalyst
Check Oxygen Sensor(s)
Check Oxygen Sensor(s) Control
Perform Oxygen Sensor(s) Aging Check

Found this on line for checking the above, but for another VW i.e. a MKIV VR6 Golf/Jetta....

http://forums.vwvortex.com/showthread.php?1265064

Just wondering if anyone knows the relevant checks for the blocks and values in the "Engine" control module with VAG-COM?

Ta!

j

Anyone?

janski wrote: Sun Jul 02, 2017 4:20 pmAnyone?

Looks like no one can give a proper answer to that question!

I thought that if you back probe a Lambda sensor and display its output on an oscilloscope, you could gauge its effectiveness by the frequency of the output "swings". An old sensor would be lazy/unresponsive and it would change values very slowly, a good sensor would respond a lot quicker. Though, I don't know exactly what constitutes "slowly" or "quickly" in terms of resulting frequency!

Edit:- I'd think if you work your way through all the channels/fields using VCDS you should find the Lambda sensor output and then use VAG SCOPE to plot its trend?

Cheers RUM4MO,

I know it was a long shot, but worth the punt. Will have a play with vagcom, but not an expert user of it so kinda stabbing in the dark.

FYI - fitting a new middle and back box, clear DTCs.
Run the Polo, see if it comes back.
Failing that, a new sensor downstream of the catalyst......then a new upstream sensor and then a new catalyst. Clearing DTCs as I go along. All lots of £££. BUT, easy DIY.

j

I suppose using VCDS in that way is what makes you become an expert, I can't say that I've done much in the way of investigating lots of things with VCDS and I've owned that - VAG-COM > VCDS since maybe late 2001! I have always intended to record lots of parameters as bench marks for the future - but so far not done that.