From Ross-Tech Wiki

16816/P0432 - Main Catalyst: Bank 2: Efficiency Below Threshold

Possible Symptoms

  • Malfunction Indicator Light (MIL) ON

Possible Causes

  • Failed ceramic monolith in Catalyst
  • Oxygen Sensor(s) defective
  • Leak in exhaust system
  • Firmware issue with ECM

Possible Solutions

  • Inspect Catalyst for internal rattle
  • Check Oxygen Sensor(s)
  • Check Oxygen Sensor(s) Control
  • Perform Oxygen Sensor(s) Aging Check
  • Set Readiness
  • Check for Leak in Exhaust
  • Check ECM for firmware updates

Special Notes

  • For Audi engine codes ART or AKB, please see TSB 26-04-01
  • For Audi engine code ATQ, please see TSB 26-08-07
  • For Volkswagen engines, please see TSB 01-07-07
  • As per TSB 01-07-54, do not replace the ECM for this DTC. Please see TSB for complete details.