Diagnostic Aids
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Inspect for the following conditions:
- A stuck open EGR vacuum vent solenoid.
- A stuck open EGR valve vacuum control solenoid.
- Proper vacuum line connections.
- A restriction in the exhaust system causing high back pressure.