Checks 
 | Action 
 | 
DEFINITION: White,
black, gray or blue smoke under load, idle or start up hot or cold. 
 | 
Preliminary
Check 
 | 
|     •  | Make sure the vehicle has an actual problem. |  
  
 | 
Fuel
System Checks 
 | 
 | 
Sensor
Check 
 | 
|     •  | Check the engine coolant temperature (ECT) sensor by using the
scan tool in order to compare the engine coolant temperature with the ambient
    air temperature on a cold engine. If the coolant temperature reading is
  more   than 5 degrees more or less than the ambient air temperature on 
 a cold   engine, check for a high resistance in the coolant sensor circuit
  or the  sensor  itself.  |  
  
|     •  | Check the glow plug system operation. |  
  
 | 
Air Intake
System Check 
 | 
|     •  | Check the air cleaner and the air intake ducts for a restriction. |  
  
|     •  | Check for a restriction in the turbo charger inlet duct. |  
  
|     •  | Check for a restriction in the intake manifold. |  
  
 | 
Engine
Mechanical Check 
 | 
|     •  | Check for incorrect basic engine parts such as the cam, the heads,
the pistons, etc. |  
  
|     •  | Check for any excessive oil entering the combustion chamber. |  
  
 |