Diagnostic trouble code

P0430 Catalyst System Efficiency Below Threshold, Bank 2

The PCM sees downstream oxygen-sensor behavior that suggests bank 2 catalyst efficiency is below threshold.

Catalyst Efficiency Codes

Read This First

This code identifies the failed diagnostic test or circuit family. Confirm the basic checks before replacing parts, and keep freeze-frame data until the repair is verified.

Common Checks

  • Fix misfire, fuel-trim, or oxygen-sensor codes first.
  • Check for exhaust leaks on bank 2.
  • Compare upstream and downstream oxygen-sensor switching.

Common Repairs

  • Repair engine-running faults that can overheat the converter.
  • Repair exhaust leaks or sensor wiring problems.
  • Replace the bank 2 converter only after the root cause is fixed.

Mustang Notes

Model-Year Applicability

Listed for 1996 and newer traditional gasoline Mustang pages in this first-pass catalog. Engine, calibration, and Ford-specific codes may narrow that range as more service data is added.

Sources

  1. SAE J2012DA Digital Annex of Diagnostic Trouble Code Definitions
  2. 1996 Ford Mustang Owner Guide