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.

This DTC does not set for an idle condition.

A number of conditions may cause DTC P0087 and DTC P1093 to set:

Excessive fuel return to the tank.
A fuel injection pump failure.
A fuel pressure regulator (RPCV) failure.

If you have to prime the fuel system, check for the following conditions:

A restricted fuel supply line.
A fuel supply line air leak. Diagnose fuel system. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 6.6L SIERRA & SILVERADO - DIESEL article.

A sticking fuel pressure regulator may set this DTC. Diagnose fuel system. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 6.6L SIERRA & SILVERADO - DIESEL article. If the condition is determined to be intermittent, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.