GM Service Manual Online
For 1990-2009 cars only

Listed below are inspections that should be performed at the specified intervals. Make any necessary repairs at once.

High Pressure Regulator (HPR) Coolant Hose Inspection

Inspect the high pressure regulator (HPR) coolant hoses twice a year (for example, spring and fall). Replace the hoses if they are cracked, swollen, or deteriorated. Inspect all fittings and clamps. Replace the fittings and the clamps if necessary.

CNG Fuel System Leak Inspection

Inspect the CNG fuel system for leaks once a year using an electronic or liquid leak detector. If a leak is found, replace the O-ring face seal (ORFS), fuel line, or component as required.

CNG Fuel Tank and Brackets

Every three years or 60 000 km (36,000 mi), whichever occurs first, inspect the CNG fuel tank and the mounting brackets for cracks, corrosion, or other damage. Replace the tank, brackets, and/or fasteners as required. Record the inspection date and the results in the CNG Fuel Tank Inspection Record in the owner's manual supplement.