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2008 GMC Sierra Denali Problems

RepairPal has identified the most common problems with the 2008 GMC Sierra Denali based on complaints from actual vehicle owners. We'll tell you what the problem is and what it'll take to fix it.

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10
Known Problems

The GMC Sierra Denali is known to have issues with the EVAP system, a part of your emission control system.

The EVAP canister vent valve or valve solenoid wiring may fail causing illumination of the check engine light, setting code P0446, and problems filling the tank with fuel.

To correct the issue, the EVAP canister vent valve, solenoid, and wiring must be inspected. The most common fix is replacement of the wiring connector or replacement of the vent valve assembly.

The GMC Sierra 1500 Denali uses a throttle position sensor (TPS) which commonly fails and causes:

This issue is related to the throttle position sensor, and can be caused by faulty wiring to the TPS, bad connection at the TPS, or a failed TPS.

To correct this issue, the wiring harness, connector, and throttle position sensor must be inspected, tested, and/or replaced. The most common cause is a faulty TPS.

Illumination of the Check Engine Light can be caused by a loose or worn gas cap.

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

Our technicians recommend flushing the brake fluid every 60,000 miles.  Brake fluid that is dirty may cause problems in the brake system.

A poor electrical ground under the battery tray may cause the ABS warning light to illuminate. Our technicians tell us that cleaning and properly securing this ground and also the main ABS ground on the frame rail below the drivers door may be necessary.

Extended life coolant may become contaminated and require cooling system service before the recommended 100,000 miles.
Our technicians highly recommend that the transmission is serviced every 30,000 miles to avoid problems and maintain optimal operating order.

The keyless entry system may stop working. Our technicians tell us the key fobs and keyless entry receiver may need to be replaced to correct this fault.

The speedometer or other instrument panel gauge may begin to work erratically at times. Our technicians tell us that the instrument cluster must be sent to a repair facility to correct this fault. The warranty has been extended on some of these units to 7 years or 70,000 miles.