May as well start a new thread with a new issue after replacing all Oxygen sensors, spark plugs, and doing a MAF cleaning (surprisingly easy!).

Discovery has 206, 500 Km, and the top end of engine rebuilt about a month ago. Was suffering massive blow by for about 5 years due to wrong oil (now using 76 Guardol ECT 15w40, just as good if not better than rotella).

Cats were replaced five years ago just before blow by began happening with after market cats.

Presently after the MAF cleaning my CEL threw a p0430 code... I suspect my cat(s) failing since they were polluted over those 5 years.

Does the p0430 code suggest one or both of the cats are failing?

 

Here is the GEMS ecu manual. Page 7 starts the section on catalyst monitoring, that code is for bank 2. Now you would think that one will be just about as dirty as the other. We have had posts about removing the cats and soaking them to wash out the impurity and renew them.

 

Hello Savannah Buzz,

Thank you for your time, reply and input

I think that I will replace the cats along with my muffler (muffler needed replacing based on the visual inspection and sound).

Magnaflow 99005HM

Should only cost $400-$500 for all that.

 

Well, $500 should just about cover some CATS. But take a look at this video on code 420, may not be cats.

Frequently Asked Question 05 -- Troubleshooting the PO420 Code Error - YouTube

and

More Information for EASTERN CATALYTIC 40460

 

Just a follow up to this issue. I cleared the code(s) I had last week and they have not come back yet... I do know that I snapped one of my leads on the head of one of the spark plugs which I have replaced the wires with Kingsborne 8mm leads.

Fingers crossed