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

[Berg]

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

Anyone experienced this code can you tell me what the problem was?

Its been popping up for the last 2 months now, i had the car mot'd 3 weeks ago where it succesfully passed emmisions test so it cant be my sports cat and surely a lambda would effect emissions?

Wideband gauge shows fueling is correct so its not running lean or rich either

 

[tom w]

I had a similar code when my maf was playing up have you logged the airflow ?
I was getting bank 1 codes off that

 

[NAB_ARCK_86]

Check manifold bolts on top mine are foreva coming lose

 

[Berg]

I havent logged airflow but i literally replaced the maf 2 weeks ago as it failed. All codes were cleared when i put the new one on

Ive heard exhaust leaks can cause it yer ill give the manifold a check tomoz make sure its all good

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