Amber engine light on dash board

[xivisonx]

my lambda sensor was just recently changed, my OSDII came today, it said P0420 - Catalyst System Efficiency Below Threshold Bank 1. So looks like my cat is dead, nothing else came up. So if that's the case, a decat and remap will be on the cards.

 

[MarcB]

If the lambda sensor that you changed was not a genuine Renault one or a Genuine Bosch one this might cause the problem also.
I would also change to make sure it was fitted correctly and that the connector plug was not damaged or wet.

 

[Carbon Chaos]

Which lambda sensor was recently changed ? there are two in the exhaust one before the cat and one after.

My best guess is the downstream lambda sensor has failed - Only use genuine sensors as after market ones can trigger false readings in the ECU.

Never use any copper grease near a sensor either as this will contaminate the sensor when its working.

 

[Mikeyjp]

Driving to work and the dreaded orange engine light came on

 

[liamkirkham]

I bought one of the readers suggested earlier in this post as my light keeps coming on for a few days before going off for a few.
It says it's the O2 sensor circuit which I believe to be the lambda sensors but is there any way of telling whether it's the lambdas or the cat?
as the recent emissions test showed them to be very high!

 

[Cento186]

I bought one of the readers suggested earlier in this post as my light keeps coming on for a few days before going off for a few.
It says it's the O2 sensor circuit which I believe to be the lambda sensors but is there any way of telling whether it's the lambdas or the cat?
as the recent emissions test showed them to be very high!

It should either refer to Bank 0 or Bank 1, which of course is Pre and Post-Cat.

If it's not the pre-cat sensor it would suggest the cat is fubar, if the emissions are too high.

 

[liamkirkham]

Thanks Cento, iirc it said it was Bank 0 but I might replace both sensors to make sure and hopefully that does it.

 

[xivisonx]

My post cat lambda sensor was the one that got changed, it was genuine so the chances of it dying already are pritty slim? I cleared the light for now, but I'm just trying to find out as much info as I can before buying the parts.

 

[Mikeyjp]

mine has came back as being Cat Emissions, they have cleared the fault will have too see if it returns

 

[gungo]

I've had this light on and off for a while. Off for a while now.
After reading this thread, I bought a mini ODB2 bluetooth scanner tool (£5.99) and the Torque app.
All seems to work fine but i was surprised that there are no faults listed, has been a month or so since the light came on but I would think that it should stay in the memory somewhere.
Anyone know how the fault codes work on the Clio.

Scan tool and app are pretty amusing for less than a tenner and will hopefully come to some use in the future.