Engine management fault

[trueblue]

I have had the engine management light come up and when checking with a reader it says :
Catalyst system efficiency below threshold (Bank 1)
I have a full Miltek system, 4-2-1, Sports cat, mid section & rear box and running with a K&N induction filter.
Basically what does this fault mean ?
The car seems to be running fine at the moment but I really want to understand the issue and get it sorted.

Thanks.

 

[madhillbilly17]

i would say its either the cat or the lambda how old and how many miles has the cat done,its probably more likely to be the lambda sensor tho the 4-2-1s seem to eat them abit more than the std manifold.

 

[trueblue]

Not sure how many miles its done. Bought the car with it all fitted. I would guess it has not done too many miles as I think it had only been on the car for a year or so.
If the lambda was at fault would this not affect the driveability, poor acceleration or idle ?

 

[madhillbilly17]

no not to start with,then it will give a cut in power for a few seconds now and again and it slowly gets more often and for longer,well thats what mine did anyway.

 

[trueblue]

Ok m8. Thinking about the lambda's I will check the wiring out as they have been extended and might not be done to the best quality. I'm sure when I was looking the other day at something else the electrical tape seemed to be covering a "choc block" connector. Might just rewire and solder them anyway.
Thanks.

 

[Ginger Tom]

Be a good idea to get rid of that chocolate block k:

 

[trueblue]

Yeah you are right there Tom. Cant believe it hasn't melted yet :grin:

 

[trueblue]

Just done a bit of digging on the net.

Catalyst System Efficiency Below Threshold (Bank 1)

Causes.
Damaged or failed oxygen sensor (HO2S)
Downstream oxygen sensor (HO2S) wiring damaged or connected improperly
Engine coolant temperature sensor not working correctly
Damaged or leaking exhaust manifold/ cat/ exhaust pipe
Retarded spark timing
Oxygen sensors in front & behind the cat reporting similar readings
Leaking fuel injector or high fuel pressure
Cylinder missfire
Oil contamination