One or more fuel injectors may become stuck closed causing an engine misfire and the Check Engine Light to illuminate. Our technicians tell us that this problem can be caused by some fuel additives. There are special procedures which may be able to restore the affected injector. If this fails the affected injector must be replaced.
1999 GMC Yukon Denali Problem Reports
RepairPal Verified 1999 GMC Yukon Denali Problem Reports
The engine may develop a misfire due to worn valve seats. This fault will cause the Check Engine Light to illuminate. Our technicians tell us the misfire may or may not be felt while driving. They further recommend that both cylinder heads be removed and thoroughly inspected and repaired as necessary.
A Loose or worn gas cap may cause Check Engine Light to illuminate.
The front or rear differential may develop an abnormal noise due to worn bearings or another internal fault. Our technicians tell us that a complete overhaul of the affected differential is commonly necessary to correct this condition.
The intake manifold gasket may develop and external engine oil or coolant leak. In some cases, an internal coolant leak may occur causing coolant to mix with the engine oil. Running the engine with a coolant/oil mix may result in engine damage. Replacing the intake manifold gasket should correct this issue.
The alternator may fail causing the battery to go dead. The charge light on the dash may or may not illuminate. The alternator may also develop an abnormal noise. A failed alternator will require replacement.
The 4WD transfer case encoder motor position sensor or the selector switch may fail causing the service 4WD message to be displayed. Fault code(s) stored in the transfer case control module will be of assistance in determining the exact fault causing the message to be displayed.
Vehicles equipped whit a 4 speed automatic transmission may develop a harsh 1-2 shift and/or illumination of the Check Engine Light with code P1870 stored. This can be caused by wear of the bore for the TCC isolator and regulator valves in the valve body. This condition does not commonly occur until the transmission reaches normal operating temperature. If the valve body is worn, replacement will be necessary to correct this concern.
Power brake systems using "hydro-boost" may leak power steering fluid from the hydro-boost unit located behind the brake master cylinder. Replacement of the hydro-boost unit is the common repair to correct this concern.
One or more heater & AC (HVAC) temperature and/or air delivery mode door actuator may fail, resulting in improper temperature or air delivery. If this occurs, fault code(s) should be stored in the HVAC control module which should assist in diagnoses.
A clicking noise may be noted from the turn signal flasher after the turn signals are switched off. This is commonly cause by a faulty turn signal switch which will require replacement.
The upper dash may crack, most commonly on vehicles in warm climates and exposed to a lot of sunlight. The common repair is to replace the upper instrument trim panel. Information on a technical service bulletin or extended warranty is not available at this time.
The quick-connect fittings for the heater hoses tend to leak engine coolant. This problem commonly occurs because the metal housing has become brittle, which can break and cause leaks.
The air conditioning compressor may develop an abnormal noise and require replacement. We recommend that whenever an AC compressor is being replaced for a noise condition, a filter kit should be installed to prevent any metal particles in the system from damaging the new compressor.
The power door lock actuators may become slow to operate or stop working completely and require replacement.