School Bus Catalytic Converter Replacement
Updated: Sep 10
Yes, US-market school buses use catalytic converters as part of the emissions system, and the right replacement depends on the bus make, engine, and model year, not just on what the old one looks like. This school bus catalytic converter guide covers fitment for Blue Bird, IC Bus, Ford Type A, and Thomas Built, with OE cross-references so you can match by the number stamped on the old unit.
Do School Buses Have Catalytic Converters?
Yes. Gasoline, propane, and many diesel school buses use a catalytic converter, or a catalytic muffler that houses the converter, to cut emissions. The unit varies by engine and chassis, so a converter that fits a Blue Bird will not fit an IC Bus or a Ford Type A.
School Bus Catalytic Converter Fitment by Make
Match the converter to the make, engine, and year, then confirm with the OE number on the old unit. Common Auto‑jet catalytic converters by make:
Blue Bird
Auto‑jet Part # | Fits | OE Number |
BBCONV9732 | Blue Bird Vision, 2018 to 2021 | 10042603, 10049732 |
BBCONV9616 | Blue Bird skinny, 2013 to 2017 | Call to confirm |
BBCONV704 | Blue Bird | 10070704 |
400CATREV | Blue Bird with Caterpillar engines, 2002 and up | 0036277 |
IC Bus (Navistar)
Auto‑jet Part # | Fits | OE Number |
ICG502ML | IC Bus CE with General Motors engines | 6133503C4, 6133503C5 |
ICG504MR | IC Bus CE with General Motors engines | 6133504C3, 6133504C4, 6133504C5 |
350400CAT | CE International conventional, 2005 and up, catalytic muffler | 3585872C1, 3589192C1 |
ICRESICAT and ICRESIALZ | IC rear-engine VT-365 and DT466, 2004 and up, catalytic muffler | Call to confirm |
NAV981R | International, 2007 and up | 2593981R91, 2595714C91 |
Ford Type A
Auto‑jet Part # | Fits | OE Number |
FORDCONV6 | Ford E-350 and E-450 6.0L, 2004 to 2008 | 5C2Z5E212B |
FORDCONV212A | Ford | GC2Z5E212A |
FORDCV212-B | Ford | LC2Z5E212B |
FORD250CONY | Ford Transit-250 3.7L, 2015 to 2019, Y-pipe with three converters | GK4Z5F250F |
Thomas Built
Auto‑jet Part # | Fits | OE Number |
TMVPFOA72 | Thomas Built, 2007 to 2010 | Call to confirm |
TMVP400CAT | Thomas Built with Cummins engines, 1994 and up. 4 inch inlet | Call to confirm |
TMVP1249 and TMVP1250 | Thomas Built catalytic muffler, 2004 and up | Call to confirm |
Blue Bird and Thomas buses from 2007 and up also use the 400CATSI universal 409 stainless catalytic muffler (OE 1777556, 174078). For the muffler-integrated units, see how to measure a school bus muffler.
Catalytic Converter or Catalytic Muffler?
On some buses, especially IC Bus CE, rear-engine International, and many Thomas units, the converter is built into the muffler as a single catalytic muffler rather than a standalone converter. When you replace it, you replace the muffler and the converter together. If your parts list shows a catalytic muffler, order that assembly, not a separate converter. For IC-specific options, see our IC Bus exhaust parts.
How to Identify the Right School Bus Catalytic Converter
Work in this order:
Start with the make, engine, and model year.
Read the OE number stamped on the old converter or muffler and cross-reference it.
Confirm whether the bus uses a standalone converter or a catalytic muffler.
Match gas, diesel, or propane, since the converter differs by fuel.
Send us the make, engine, year, and OE number and we will confirm the correct part. Call 800‑247‑5391 or request a quote.
Frequently Asked Questions
Do school buses have catalytic converters?
Yes. Gasoline, propane, and many diesel school buses use a catalytic converter or a catalytic muffler that houses the converter to reduce emissions. The unit varies by engine and chassis, so a converter that fits one make will not fit another.
How do I find the right catalytic converter for my school bus?
Match by make, engine, and model year, then confirm with the OE number stamped on the old converter or muffler. Also confirm whether the bus uses a standalone converter or a catalytic muffler, and whether it runs gas, diesel, or propane.
What is a catalytic muffler?
On some buses, such as IC Bus CE and many Thomas units, the catalytic converter is built into the muffler as a single catalytic muffler. You replace the converter and muffler together as one assembly rather than as separate parts.
Can you cross-reference my OE catalytic converter number?
Yes. Send the OE number stamped on the old unit along with the bus make, engine, and year, and Auto‑jet will confirm the correct catalytic converter or catalytic muffler.
