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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 258 (Engine Controls Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0420: TWC System - Low Efficiency >> Diagnostic Aids

Diagnostic Aids

WARNING: This page is about a different car, the 2003 GMC Sonoma and 2003 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.

Thoroughly check any circuitry suspected of causing the intermittent complaint. Inspect for a poor connection, rubbed-through wire insulation, a wire broken inside the insulation, backed out terminals, improper mating or broken locks. Check for physical damage to the wiring harness.