BOBCAT-P0420 moderate Bobcat ›

Oxidation Catalyst Efficiency Below Threshold

The BOBCAT-P0420 (Bobcat) diesel fault code means: Oxidation Catalyst Efficiency Below Threshold. This is a moderate severity code.

My Garage →
Keep driving?
Yes, but fix soon
DIY difficulty
advanced
Estimated cost
$1,500-$4,500

What Are the Symptoms of BOBCAT-P0420?

  • DPF regen more frequent
  • Slight power reduction

What Causes BOBCAT-P0420? (Most Likely First)

  • DOC substrate aged / contaminated with fuel Likely
  • Leaking injector raw-fueling the DOC Possible

Can I Still Drive with BOBCAT-P0420?

Yes, but fix soon. BOBCAT-P0420 is rated moderate severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring it.

Frequently Asked Questions

What is Bobcat code P0420?

Bobcat P0420: Oxidation Catalyst Efficiency Below Threshold. This code is reported on Bobcat equipment running the described engine family.

Can I keep working with Bobcat code P0420?

Usually drivable short-term, but fix soon to avoid derate or DPF issues.

How much does Bobcat P0420 cost to fix?

Estimated repair cost: $1,500-$4,500. Off-road diesel shop labor runs $125-$175/hr in 2026. Dealer diagnostic software (Bobcat Service Analyzer) is usually required.

Mechanics Guide Step-by-step diagnosis

How Do You Diagnose BOBCAT-P0420?

  1. Check DOC inlet vs. outlet temperature delta during regen.

  2. Inspect for injector copper washer failure that raw-fueled DOC.

Sources 1

This page is built from documented references. Verify against your own service info before repair work.

  • SAE J2012Diagnostic Trouble Code Definitions (defines P0420 as a generic OBD-II code)

P0420 on Other Platforms

The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown:

Gas / Automotive (OBD-II) Generic OBD-II definition for P0420 Duramax serious Catalyst System Efficiency Below Threshold Bank 1 Hino serious Catalyst System Efficiency Below Threshold (DOC) Isuzu serious Catalyst System Efficiency Below Threshold (DOC) PACCAR serious Catalyst System Efficiency Below Threshold Bank 1 Yanmar moderate Oxidation Catalyst Efficiency Below Threshold

Which Vehicles Commonly Get BOBCAT-P0420?

  • Bobcat S650 skid steer loader (Kubota V3800)
  • Bobcat S740 / S750 / S770 / S850 skid steer loaders (Kubota V3800)
  • Bobcat T650 / T750 / T770 / T870 compact track loaders (Kubota V3800)
  • Bobcat E50 / E55 / E60 / E85 mini excavators (Kubota V3800)
  • Bobcat UW56 utility vehicle (Kubota V3800)

Explore More

More Bobcat codes → Diesel home All diesel codes Heavy-duty Guides

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