1998 GMC Sonoma Problems

RepairPal has identified the most common problems with the 1998 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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Known Problems

The HVAC blower motor may stop working at one or more speeds due to a faulty blower motor resistor block. Our technicians recommend to confirm the resistor is at fault by first checking the operation of the switch.

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.

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.

A fluid leak may develop from the transmission output shaft seal. This leak may cause the transmission mount to become oil soaked and require replacement of the mount along with the leak repair.

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.

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

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 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.

A door window may move slowly or stop in mid travel due to a failing power window motor. The affected window may start working again after the motor cools off. Replacing the faulty window motor will commonly correct this concern.

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.

GM recommends replacing the engine coolant at 100,000 miles; however, our technicians tell us that the coolant may become contaminated and require a complete cooling system flush every 60,000 to 70,000 miles.

Our technicians highly recommend that the transmission is serviced every 30,000 miles to avoid problems and maintain optimal operating order.

This engine may leak oil from the valve cover gasket.