Catalyst system efficency below threshold?

[karnovking]

My 01 Odyessy is reading code PO420 Catalyst system efficency below threshold.

Can someone tell me what this means?

[UncleBob]

Originally Posted by karnovking

My 01 Odyessy is reading code PO420 Catalyst system efficency below threshold.

Can someone tell me what this means?

it means your cat is bad, most likely.

[shorod]

There are a few items that can cause such a diagnostic code. Check the following before condemning any one part:

• Use of leaded fuel
• Damaged HO2S
• Malfunctioning ECT
• High fuel pressure
• Damaged exhaust manifold
• Damaged catalytic converter
• Oil contamination
• Cylinder misfiring
• Downstream HO2S wires improperly connected
• Damaged exhaust system pipe
• Damaged muffler/tailpipe assembly
• Retarded spark timing

Does your van run fine, or seem low on power?

You should also search the Odyssey forum for the code to see if there are common causes for this code on your specific vehicle.

-Rod

[karnovking]

yeah, it runs fine. I cleared the code. Have taken the van about 200 miles now and the code has not come back. so i'm now playing "wait and see"