P0420 p0430 catalyst below threshold

[Smithky]

Hi all been having this code come up for ages. We have replaced both cats with genuine ones have put 3 sets of o2 sensors in updated ecm calibrations from tis2web cleaned mag sensor changed plugs changed injectors replaced evap purge solenoid and it’s still coming up I’m all out of ideas I’ve attached graphs of the o2 sensors for reference one is of the car with errors and the other is of another ve that has no codes

 

[crew chief]

Still running factory exhaust manifolds?

 

[Smithky]

According to the exhaust shop they are. But the o2 sensors at the front are located diffrent then the other ve so the one with the issue is a 2008 omega with ly7 motor and the o2 sensors are at top of manifold and the other is 2008 omega with Leo engine and top o2 sensors are near the cat attached photos

 

[07GTS]

fronts are ment to move up/down as they are controlled by the ecu for closed loop, looks like they are working, if its cat efficiency then it will be an exhaust issue or something, after u rest the code how long till it comes back ? the rear 02's dont seem to be doing much they should be moving a little but not as much as the front, if they dont operate right it may cause the cat codes

 

[lmoengnr]

Make sure the joint between the headers and cats aren't leaking.

 

[Smithky]

There’s no leaks this is 3rd set of cats we have put on and they all have thrown error codes the last pair blew out there was chunks of cat in the exhaust it was replaced under warranty the shop claims there genuine

 

[Fu Manchu]

Have you tested the integrity of the harness between the sensors and ECM?

Cooling system integrity ok? Pressure test check out on it? Maybe coolant is contaminating the cats?

Check your PCV if it’s blocked. Do the mod. Maybe oil is going through and contaminating the cats?

 

[Fu Manchu]

These guys do a lot in the automotive training field. Not just any random video. It might help? It might not?

 

[Smithky]

Cheers for that i shall test the harness and check out the video and get back to you.. pcv isn’t blocked either. What’s the mod
You’re talking about ? Tia

 

[Smithky]

fronts are ment to move up/down as they are controlled by the ecu for closed loop, looks like they are working, if its cat efficiency then it will be an exhaust issue or something, after u rest the code how long till it comes back ? the rear 02's dont seem to be doing much they should be moving a little but not as much as the front, if they dont operate right it may cause the cat codes

About a day or two