Emu Code P0420

[amanda]

Catalyst Efficency Below Threshold Bank 1, any ideas what I should check first.

[stef123]

Catalyst Efficency Below Threshold Bank 1, any ideas what I should check first.

It could be a leak in the exhaust system around or before the cat, damaged cat or faulty lambda sensor.

[amanda]

I reset the EML and it stayed off for a couple of months, It came back on again today so I have reset it again but need to know what I should check first. I noticed a bit of plastic came out of one of the ht leads when I was checking them, should I change the HT leads first.

[dezwez]

I reset the EML and it stayed off for a couple of months, It came back on again today so I have reset it again but need to know what I should check first. I noticed a bit of plastic came out of one of the ht leads when I was checking them, should I change the HT leads first.

have you just had a new cat put on and was it manfactors o.e.m

[dezwez]

have this same code thrown up on my focus

P0420 Catalyst System Efficiency Below Threshold (Bank 1) and it just passed a mot with light on and this cat on the car which is not oem.

read this.

(1)

Error codes thrown by your cars computer that indicate a bad catalytic converter, actually originate from the oxygen sensors. Typically, a car has an oxygen sensor upstream and downstream of the converter. The upstream converter is used to feedback information to your cars computer, allowing it to make sure that your engine is running optimally. The downstream sensor's only use is to test how well your converter is working. If your converter is shot, it may still be possible for you to create a condition that makes your downstream oxygen sensor think that it is actually working. This fix requires that your oxygen sensor is in working condition.

2

Disconnect your cars battery. This will reset the computer and clear the existing error codes. Locate the oxygen sensor that is downstream (closer to the tailpipe) of the catalytic converter. Remove the sensor, and take to your local car parts store. Find the part called a spark plug defouler. The threads on your spark plugs match the threads on your oxygen sensors, thus the sensor will be able to thread into the back of the defouler. Buy 2.

3

Measure the diameter of the tip portion of the oxygen sensor that extends past the threads. Select a drill bit that is slightly larger than this diameter, but still smaller than the defouler threads. Put the defouler in a vise, and drill it out until you have removed enough material to allow the sensor to screw all the way into the defouler. Be careful not to drill through the end of the defouler, as you do not want to increase the size of the small hole in the end of the defouler. drill bit size 1/2"i think.

4

Now, thread the drilled out defouler into the exhaust pipe where the oxygen sensor was removed from. Install the oxygen sensor into the defouler, and reconnect the wiring and reconnect the battery. Your car is ready to start, and will no longer throw any error codes related to the catalytic converter.

Read more: How to Clear Catalytic Converter Codes Without Replacing Your Catalytic Converter | eHow.com http://www.ehow.com/how_5237592_clear-codes-replacing-catalytic-converter.html#ixzz1hrnxedcj

this is the site i have order one from

http://www.o2-simulators.com/?gclid=CJPDueT9rK0CFUIMfAodZHMjoA

ps only just seen your post

[amanda]

Wow thankyou this is taught me a lot, as soon as the wind dies down I will have a look. The car is running fine the only complaint I have is first thing on a morning when it's cold it seems to make what can only be deescribed as few clicking an sucking noises which disapear once the engine is warmed up.

Thank you your a star. :)

[dezwez]

Wow thankyou this is taught me a lot, as soon as the wind dies down I will have a look. The car is running fine the only complaint I have is first thing on a morning when it's cold it seems to make what can only be deescribed as few clicking an sucking noises which disapear once the engine is warmed up.

Thank you your a star. :)

your welcome :)