Kubota Catalyst Kit (DOC) 1J801-18940 | Genuine Kubota Exhaust Aftertreatment

Part number 1J801-18940 is the genuine Kubota diesel oxidation catalyst (DOC) kit for Kubota’s Tier 4 Final compact equipment. The DOC is the first stage of the exhaust aftertreatment system. It oxidizes carbon monoxide and unburned fuel in the exhaust stream and builds the heat the system needs to regenerate the diesel particulate filter behind it. When the catalyst face plugs with soot, gets contaminated by coolant or engine oil, or can no longer pass Kubota’s aftertreatment tests, the machine will fight you with regen problems, derates, and repeat fault codes until the catalyst is replaced. This listing is for the new, genuine Kubota kit, supplied by Valley Fuel Injection & Turbo, an authorized Kubota dealer in Woodland, California.

Application & Fitment

Kubota lists catalyst kit 1J801-18940 under the Diesel Particulate Filter diagram groups for the following machines:

• Kubota KX057-4 compact excavator
• Kubota U55-4 compact excavator
• Kubota R530 compact wheel loader

These machines run Kubota’s V2607-CR Tier 4 Final common rail engine, so this is the DOC kit that serves that engine family in the applications above. Be aware that Kubota uses several look-alike catalyst kit numbers for other engine specs, and the newer dash-5 machines (KX057-5, U55-5, R540) take a different kit number. The kits are not interchangeable. If you are not certain which kit your machine needs, call us with your machine model and serial number and we will verify the correct part against the Kubota parts system before anything ships.

Frequently Asked Questions

How do I know the DOC on my Kubota needs replacement?

Typical signs are regens that run constantly or never complete, aftertreatment fault codes that come right back after a forced regen, power derates, and high exhaust back pressure. If the engine has pushed coolant or oil into the exhaust, plan on replacing the catalyst, because a contaminated DOC does not recover. Fix the root cause first, then install the new kit, or the replacement will fail the same way. We are happy to talk through the diagnosis at 530-668-0818.

Will 1J801-18940 fit my machine?

It is listed by Kubota for the KX057-4 and U55-4 compact excavators and the R530 compact wheel loader. Other Kubota models, and the dash-5 versions of these same machines, use different catalyst kit numbers. Give us your machine model and serial number and we will confirm exact fitment before you buy.

Is this a genuine Kubota part?

Yes. This is a new, genuine Kubota catalyst kit sold through Valley Fuel Injection, an authorized Kubota dealer. It is not an aftermarket copy, and it is backed by Kubota’s genuine parts warranty.

Why Buy From Valley Fuel Injection?

We are diesel specialists, not a general parts counter. Valley Fuel Injection & Turbo has been servicing diesel fuel systems in Woodland, California since 1993, and we are an authorized Kubota dealer for engines, parts, and service. Aftertreatment trouble often traces back to the fuel side, a leaking injector or an engine that never gets hot enough to regen cleanly, and we can test and repair that in house through our diesel fuel injection services. When you order from us you get the right genuine part, verified against your serial number, from people who work on these engines every day.

Pricing & Availability

Call 530-668-0818 for current pricing and availability on Kubota catalyst kit 1J801-18940, or contact us online. Please have your engine model and serial number ready so we can verify fitment and quote the correct kit the first time.