Service bulletin - In some cases, the ECM misinterprets sensor inputs as a warm-up three-way catalytic converter (TWC) deterioration and turns the MIL on with DTC P0420 or DTC P0430 (catalyst system efficiency below threshold) stored.
There are two bulletins to address the TWC deterioration with DTC P0420 or P0430:
? 18-022, Warranty Extension: MIL Is On with DTC P0420 or P0430 (All states Except CA, CT, ME, MA, NY, and VT),
for vehicles currently registered in all states except CA, CT, ME, MA, NY, and VT. The warranty on these vehicles is
extended 6 months from the launch of this campaign (expires December 31, 2018) or 200,000 miles, whichever
comes first.
? 18-023, Warranty Extension: MIL Is On with DTC P0420 or P0430 (CA, CT, ME, MA, NY, and VT Only), for vehicles
currently registered in CA, CT, ME, MA, NY, and VT. The warranty coverage is 17 years from the original date of
purchase with unlimited mileage for the first year of this warranty extension based on the launch date of this
extension. After one year, the coverage changes to 17 years from the original date of purchase or 200,000 miles,
whichever comes first.
