Rebuild vs. replace: chipper catalytic converters

A new OEM catalytic converter for a wood chipper is one of the priciest parts on the machine — and in most cases you don't need one. Here's how to decide.

The cost math

A rebuild reuses the expensive part you already own — the housing — and replaces what actually wears out: the substrate (the catalyst-coated honeycomb inside). That's why a rebuild runs about half the cost of a new OEM converter. Same fit, same connections, back on the machine in 3–5 business days.

When to rebuild

• The housing is intact — no cracks, no crush damage. (This is the vast majority of failures.)
• The unit is plugged, sooted, or the substrate has broken down from age and heat.
• You want it back fast and don't want to pay OEM.

When to buy new

• The housing itself is cracked, crushed, or rotted through — there's nothing to rebuild around.
• The unit was physically destroyed (accident, road debris).

What about deleting the cat?

Some owners consider just removing the converter. It isn't really a third option: running without it can stress the engine, and on Tier 4 machines it often triggers a derate anyway because the engine expects the cat to be there — plus the warranty and compliance downsides. Rebuilding gets your power back without the gamble. More on Tier 4 & your cat →

First, confirm it's actually the cat →