Catalyst System Error

[xxx_mojo_xxx]

My car is hesitates briefly every now and then, when I have the throttle wide-open accelerating away at "motorway" speeds.

VWR have said that VAGCOM has logged the following error.

Catalyst System Bank 1 - Efficiency below threshold.

Any ideas, what this might be related to?  The way the car behaves seems to be something to do with the coil pack or spark plugs...but that's from a someone (i.e. me) who has trouble holding a spanner!

[bacillus]

http://wiki.ross-tech.com/wiki/index.php/16804/P0420/001056

[Saintsteve]

My car is hesitates briefly every now and then, when I have the throttle wide-open accelerating away at "motorway" speeds.

VWR have said that VAGCOM has logged the following error.

Catalyst System Bank 1 - Efficiency below threshold.

Any ideas, what this might be related to?  The way the car behaves seems to be something to do with the coil pack or spark plugs...but that's from a someone (i.e. me) who has trouble holding a spanner!

I have the same issue.. Can't Fathom the fault. What are your mods Mojo? Car type/map/intake/zorst etc

I can't see or hear any leaks or smell exhaust fumes in the cabin indicating any leaks from a possible cracked milltek downpipe  

Is it possible to test the 02 sensor.. Anyone how to do it with vcds?

Seems very intermittent, flags up maybe once a week? Is yours the same mojo?

[xxx_mojo_xxx]

I can reproduce the issue without fail at 120m/ph.

Is the oxygen sensor the one connected to the air filter pipe?

[Saintsteve]

I can reproduce the issue without fail at 120m/ph.

Is the oxygen sensor the one connected to the air filter pipe?

I think it's the one nearest the rear of the car on the exhaust. Not 100% sure but it's either that or the one on the downpipe just after the turbo. Hopefully someone might know.

I also have a PCV on its way out, whether this is linked to my error, bringing up this code intermittently. 

[xxx_mojo_xxx]

I don't have a PCV as I have the BSH blanking plate.

Also, the sensor you mention sounds more like the lambda sensor rather than the oxygen sensor.

[pandahouse68]

I reckon Lambda sensor and Oxygen senor are the same things 

and I have the same fault code P0420 too

[Saintsteve]

I reckon Lambda sensor and Oxygen senor are the same things 

and I have the same fault code P0420 too

Is yours a perminant fault code or intermittent? Do you get any warning lights? Mine doesn't?

[Rav2011]

Hi Guys,

I'm getting the exact same error ..

001056 - Catalyst System; Bank 1: Efficiency Below Threshold
               P0420 - 002 - Lower Limit Exceeded - Intermittent

I have started to get the error from when I went to stage 2 (Blueflame exhaust). I have since taken my car back to Kwik-Fit and they have confirmed that
there is no air leak in the exhaust system.

Now, i'm relatively certain that it can't be the second lambda (after the cat) as i've only replaced it a few months ago.

The only lambda that I did not replace was the pre-cat lambda, which I am now leaning towards having changed. If it the second lambda that is picking up a bad reading then I may be able to get around it with a lambda spacer.

The weird thing about it is that the problem only appears in the background (no CEL).

I do not think that all of us have bad catalytic convertors!!

[Saintsteve]

Hi Guys,

I'm getting the exact same error ..

001056 - Catalyst System; Bank 1: Efficiency Below Threshold
               P0420 - 002 - Lower Limit Exceeded - Intermittent

I have started to get the error from when I went to stage 2 (Blueflame exhaust). I have since taken my car back to Kwik-Fit and they have confirmed that
there is no air leak in the system.

Now, i'm relatively certain that it can't be the second lambda (after the cat) as i've only had that replaced a few months ago.

The only lambda that I did not replwas was the pre-cat lambda, which I am now leaning towards having changed.

The weird thing about it is that the problem only appears in the background (no CEL).

Ditto, also cant be a bad cat, or it would be a perminant error surely. Pre cat lambda? Top of the Downpipe?

I'm sure it's a sensor issue as its intermittent. I've removed my remap to see if it happens, and it still does, whether it's because it's a different cell cat to the oem version?

[Rav2011]

I was talking to a chap at AMD Technik the other day and he thinks that I may be experiencing the issue due to having a 100 cell cat.

He reckons if I had gone with a 200 cell cat I may have been fortunate enough not to have encountered the issue.

The cat appears to be heating up correctly at a temperature of about 580 degrees. The sensors i'm not sure why they are giving inconsistent readings.

The car basically has two lambda sensors, one before the cat and another after the cat. I think the one that you refer to is the second lambda (downpipe).

[xxx_mojo_xxx]

I reckon Lambda sensor and Oxygen senor are the same things 

and I have the same fault code P0420 too

Is yours a perminant fault code or intermittent? Do you get any warning lights? Mine doesn't?

No warning lights. Happens intermittently

[Saintsteve]

I reckon Lambda sensor and Oxygen senor are the same things 

and I have the same fault code P0420 too

Is yours a perminant fault code or intermittent? Do you get any warning lights? Mine doesn't?

No warning lights. Happens intermittently

Are u running a stock exhaust?

[xxx_mojo_xxx]

I reckon Lambda sensor and Oxygen senor are the same things 

and I have the same fault code P0420 too

Is yours a perminant fault code or intermittent? Do you get any warning lights? Mine doesn't?

No warning lights. Happens intermittently

Are u running a stock exhaust?

Nope, Milltek turbo back exhaust

[Saintsteve]

I reckon Lambda sensor and Oxygen senor are the same things  

and I have the same fault code P0420 too

Is yours a perminant fault code or intermittent? Do you get any warning lights? Mine doesn't?

No warning lights. Happens intermittently

Are u running a stock exhaust?

Nope, Milltek turbo back exhaust

Is everyone with this error also run a turbo back system???