Mechanics

PO421

2001 Hyundai Santa Fe

Other Category problem
2001 Hyundai Santa Fe 4 cyl Two Wheel Drive Automatic 116000 miles

After verifying the code with a scope, (.2 sec lag time), I replaced the cat with a reman along with the exhaust manifold (as it had cracks in it), and the B1S1 O2 as it was seized in the manifold. The top half of the cat substrate came out, but was clean ( no signs of melting, chipping, etc.). After clearing codes I set out to run the monitors and my PO421 code was pending and after checking Mode 6 data found it was failing worse than the original cat(255/235, where as the old cat was 249/235). I then scoped the O2's and found them to be switching almost simultaneously at a raised rpm. I called my cat supplier and he telling me to check the rear cat for blockage(I informed him that while the substrate was in two pieces, it was clean and all accounted for), yet he persists on telling me it has to be something else, even inquired if the engine had a tune up lately. The engine runs fine and is in good fuel control. What could I be missing short of getting a bad cat? A call to my local Hyundai dealer confirmed bad cat and no re flashing to address cat issues is none. Thanks for your consideration in advanced, Paul
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Paul joseph
February 7, 2008.




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