False Code 53 And/Or Engine Dieseling
Some early production Ciera models with 3.0L (VIN E) engines may show engine dieseling, or a trouble code 53 being set during extended deceleration of more than 10 seconds. If code 53 is stored in ECM memory yet "No Trouble Found" is indicated, the PROM broadcast code should be checked.
A PROM with a code of CKP should be replaced with a PROM (16042776) with code DPY for Federal models. A PROM with code CKR should be replaced with a PROM (16042782) with a code DPZ for California models.