One problem related to ignition coils failure has been reported for the 2003 Cadillac CTS. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Cadillac CTS based on all problems reported for the 2003 CTS.
While traveling at moderate speed vehicle began shaking violently and loosing power. The engine was missing on one or more cylinders. Dealer recommended replacing coil, sparkplug, valve cover gaskets and oil cooler. This seems to have been caused by a defect mentioned in cad Cts TSB id # 1609265 dated 2005. This TSB states that the crankcase vapors and engine oil will vent through the cam/valve cover seals when the crankcase ventilation system becomes blocked. The oil on this vehicle evidently vented and leaked several places including into the ignition coils causing a short. If this had happened in interstate traffic at high speeds this could have caused an accident or if the oil had leaked on very hot surfaces possibly a fire. The TSB specified kits that were to be installed to prevented this from happening. Evidently, these were never installed on this vehicle.