Smog Check Failure Due to Excessive Carbon Buildup on Cadillac Fleetwood

Excessive carbon build up in the engine combustion chambers may be the cause of a smog check failure due to excess NOx emissions. A "top engine" decoarbonization cleaning procedure will commonly correct this concern.

RepairPal Verified
Average mileage: 84,000 (84,000–84,000)
4 model years affected: 1990, 1991, 1992, 1993 more
6 people reported this problem
0 people shared problem details
Related Items:
The EGR valve or control solenoid may fail causing the check engine (SES) light to illuminate.
Everything passed except failed smog no's too high
The engine control module (ECM) electrical grounds on the front of the engine block may have hi...
The transmission may develop a harsh 1-2 shift and/or illumination of the Check Engine Light wi...
hi,i have a 90 cadillac brougham with a 5.7 liter and i think i have a vaccumm problem,i checke...

Related Content