1999 GMC Sonoma Repair and Maintenance

A guide to problems, costs, maintenance and repair for your 1999 GMC Sonoma

1999 GMC Sonoma Problems

Replace Fuel Filter Every 30,000 to Prevent Fuel Pump Failure

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.

Heater Core Under Right Side of Dashboard May Leak Engine Coolant

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.

Check Engine Light With Code P1870

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.

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