System: Powertrain (P-Code)
SAE Standard (Generic)
Family: Catalyst Efficiency Below Threshold
Code P0430: Catalyst System Efficiency Below Threshold Bank 2
Diagnostic & Technical Explanation
Code P0430 (Catalyst System Efficiency Below Threshold Bank 2) sets when the ECM compares pre- and post-catalyst oxygen sensor switching activity and finds the catalyst (or a specific catalyst brick on multi-brick systems) is no longer storing/releasing oxygen efficiently enough to meet emissions thresholds. The dominant cause is a catalyst that has aged out or been chemically poisoned (oil consumption, coolant leak into the exhaust, or leaded/high-sulfur fuel), though a persistent rich/lean fuel condition or an exhaust leak feeding false switching data can also trigger it.
First-listed procedure
Rank #1
Inspect for exhaust leaks near the oxygen sensors
Easy DIY
This is the first procedure in the authored
consideration order, not a measured cause likelihood. Execute it only when its prerequisites
and diagnostic findings support it. Its cost and labor estimates (where known), the step-by-step procedure and the
remaining 3 procedure(s) are in the licensed dataset. Ordering context.
Full family: Catalyst Efficiency Below Threshold
What this page does not show
This page publishes the fault mechanism and the code index. The licensed dataset adds, for
every one of the 15,886 codes, the full authored repair set (56,729 procedures in total)
with the fields deliberately withheld here:
- Procedures 2..n after the first-listed procedure
- Aftermarket parts cost ranges in USD (
est_parts_cost_min/max_usd)
- Professional labor-hour estimates (
est_labor_hours)
- Step-by-step diagnostic and repair instructions
- Replacement-part mappings and catalog lookups
- 6,637 manufacturer-specific OEM codes across 32 makes ($149 tier)