From Ross-Tech Wiki

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

Possible Symptoms

  • MIL on

Possible Causes

  • Failed ceramic monolith in Catalyst
  • Failed O2 sensors
  • Leak in exhaust system
  • Firmware issue with ECM

Possible Solutions

  • Inspect cat for internal rattle, replace if needed.
  • Perform Readiness test for Catalyst.
  • Confirm pre and post O2 sensor are working to design.
  • Confirm there are no exhaust leaks.
  • Check ECM to see if there is a firmware update.

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.