2003 GMC Sonoma Problems

RepairPal has identified the most common problems with the 2003 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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16
Known Problems

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 headlight switch used on the GMC Sonoma is known to fail through normal operation. Since the headlight switch is also integrated into the interior lights, a malfunctioning switch can cause issues with interior lights as well.

  • Symptoms of a failed headlight switch include:
  • Headlights and taillights failing to turn on or off
  • Interior lights flicker, or fail to turn on or off
  • Gauge cluster lighting off or flickering with headlights on
  • Parking light malfunctions  

This issue is well known with General Motors Trucks and SUVs, and is solved by testing and, if needed, replacing the headlight/dimmer switch. Bad grounding wires at the tail-lights, and dirty/corroded tow package wires can also lead to some of these issues. 

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.

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.

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 oxygen sensor can fail causing Check Engine Light illumination and the engine to run rich (burn more fuel than normal).

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.

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.

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.

Brake fluid can become dirty and may cause problems in the brake system; it should be flushed every 60,000 miles.

A cover plate on the front of the engine may develop a coolant leak, resulting in an engine overheating condition. This plate covers the location where the water pump was installed on previous versions for this engine. Replacing the gasket for the cover plate and refilling the cooling system is generally all that is required to correct this concern.

The CD player in the radio may fail. Our technicians tell us that the radio will need to be removed and sent out to a radio repair shop to correct this condition.