GMC Sonoma Problems

RepairPal has identified the most common problems with the GMC Sonoma as reported by actual vehicle owners. We'll tell you what the problem is and what it'll take to fix it.

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33
Known Problems

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.

It is common for the fuel level sensor in the fuel tank read the fuel level incorrectly. The sensor must be replaced to correct the condition. Our technicians recommend having the complete fuel pump module replaced on high mileage vehicles.

A Loose or worn gas cap may cause Check Engine Light to illuminate.

The serpentine belt tensioner can fail; it may become noisy and/or the belt may jump off. Replacement of the failed tensioner will be necessary.

The EGR valve may stick open causing a rough idle and the Check Engine Light light to illuminate. Our technicians tell us that a piece of carbon may become stuck in the valve causing this problem. Cleaning the valve will usually correct this condition, in some rare cases the valve will need to be replaced.

The spark plugs should be replaced every 100,000 miles. Our technicians recommend replacing the spark plug wires also at this time.

The spark plug wire rubber boots may get soaked with oil, causing a misfire or rough idle.

The Anti-lock brake system (ABS) control unit may fail internally causing the ABS warning light to illuminate.

Vehicles using the enhanced vortec V6 engine may be hard to start run poorly and/or use to much fuel due to a fuel leak inside the intake manifold plenum. Commonly this is caused by a leaking fuel pressure regulator or fuel line. The fuel system will need to be pressurized with the upper intake manifold removed in order to determine the exact cause of the leak. Removing the "tuning valve" from the upper intake can allow for limited visual inspection without removing the upper intake manifold.

An engine oil leak may develop from the distributor shaft o-ring seal.

The distributor may develop internal faults. This can cause a rough running engine or stalling condition and the Check Engine Light may or may not illuminate. The distributor should be overhauled or replaced to correct this concern.

The fuel pump may fail causing the engine to stall and not restart. Our technicians recommend replacing the fuel filter every 30,000 miles to help prevent undue strain on the fuel pump.

The electrical contacts in the ignition switch may fail and result in erratic instrument panel gauge operation or illumination of the Check Engine Light. A failed ignition switch will require replacement.

The heater core under the right side of the dashboard may leak engine coolant which can puddle on the passenger front floor. The loss of coolant may cause an engine overheating condition. Our technicians tell us that removal of the dash board is necessary to replace the heater on these vehicles.