'02 Avalanche thew a P0430

[Falcon_LS]

Recently did a full 100,000 mile service on this truck, which included replacing the upper O2 sensors. There was a CEL...buddy said he had the truck diagnosed and these were faulty.

After replacing the upper sensors, the code went away for a good while (over a week and 1,000+ miles). This morning, the CEL came back on, so I went over to his place with my laptop and ScanXL software. Turned out to be a P0430, which points to bank 2:

Quote:
Catalyst System Efficiency Below Threshold (Bank 2)


Where is cylinder number 1 located (to help locate bank 2)?

It's the 5.3L Vortec. Thanks!

I'm going to check the system for any leaks, but I'm thinking this could possibly be the catalytic converter (O2 sensors already replaced), as the engine was run on 20W-50 SJ-rated oil until I changed it to Motorcraft Syn Blend...although it does not burn any oil.

 

[Trav]

Bank 1 is is on the left (drivers side).The rear O2 sensors are more likely the cause of a PO430.Take a temp reading before and after the cat with a infrared thermometer,look for about 100f difference @ 2500rpm.At idle it could be as little as 30f.

200f would indicate a rich a mixture and a 500f would indicate a lean mixture,these are approximate figures.
No difference between the inlet and outlet or plugging would indicate a bad cat.

Many cars have a habit of throwing PO430 with perfectly good cats using aftermarket O2 sensors,using Denso or Standard usually takes care of it.Bosch and universal fit types are in my personal experience the culprit more often than not in these cases.

PS I have seen a few PO430 cases cleared up using a high quality fuel treatment like Regane,Amsoil pi,redline.

 

[JHZR2]

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