Fault Family
System: Powertrain (P-Codes)
2 SAE Codes
HC Adsorption Catalyst Efficiency
Diagnostic & Technical Explanation
Code P2423 (HC Adsorption Catalyst Efficiency Below Threshold Bank 1) sets when the ECM's cold-start hydrocarbon trap monitor finds the adsorption catalyst is no longer capturing and later burning off unburned hydrocarbons during the first seconds after a cold start as effectively as its calibrated threshold requires. Causes are thermal aging of the adsorption bed's washcoat from repeated heat exposure, physical substrate damage, or an exhaust leak upstream of the trap diluting the sample the ECM uses to judge efficiency.
These 2 diagnostic trouble codes share one
detection mechanism and one repair path, which is why MechanicDB groups them into a single
authored fault family rather than repeating the same explanation 2 times.
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)