I have a 03 disco that is throwing a PO420 and my SAI (secondary air pump) is making lots of noise. I could change the filter, but I need to know if that could be related to the PO420 code I am throwing. All my O2 sensors are new and sea foam induction cleaning has been recently done. Any thoughts?

 

Did you do the intake cleaning with the new O2 sensors installed?
Sending all of the crud through the cats and new sensors may have damaged them, it is a good idea to disconnect the cats from the manifolds when you do an intake cleaning that way all of the crud isnt sent through the cats/sensors
Read this
http://www.obd-codes.com/p0420

 

420 is a bad cat, below effeiceny on the drivers side. How many miles on it?

 

I did to the deep induction cleaning per Mike's instructions after I replaced the O2 sensors. No mention of disconnecting the Cats. It has 114K. If it is the Cats- is there any other good option besides OEM Cats for $3K? used? aftermarket?
Also, is there any way the SAI pump malfunctioning could cause the PO420? Thanks.

 

The Seafoam did not hurt your cats. Something from long ago, like failed head gaskets or a bad misfire started this.
Look for a site like this for great cats, and with your mileage, consider replacing both.

http://www.completeexhaust.com/produ...roducts_id=184

 

SO the SAI pump always being on could not have thrown the PO420 code? I want to be positive it is the cats. The air solenoid valve was bad. I replaced it and the problem stopped. So I reset the CEL and hope I'm good to go.

Also, if it is the cats, these universal cats are a GREAT(?) replacement? They seem like generic universal cats. You recommend this brand? You have had great experience with them? I don't want to be replacing them in 6 months or have my car running poorly. Please answer me on each of these. Thanks!

 

Mike- you also mentioned head gasket or misfire as reason for bad cats. I don't think I have either, but how would I know if my head gasket is starting to go? I have no smoke, no water in my oil, but maybe a mild oil leak around head gasket area.

If i replace the cats and still have an issue, I could be back here in 6 months right? What else could cause my cat to be bad beside head gasket or misfire? Thanks.

 

Please see my last reply. The code came back this week (420/430/1590). Anything else I could check? SOunds like I have a California compliant car so I need the more expensive CA cats? Magnaflow makes one for $199/ea from complete exahust. any other recommends?

 

Replace the rubber mountings on the pump, they get hard after a while and vibrations reverberate through the body. $12/ea on the web. instant fix for noisy SAI. You can test before you buy, just unbolt the pump and hold it (tight) away from the mounts while someone starts the engine.