Diagnostic Aids

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.

High resistance in the circuits of the component may set DTC P0300 without setting the DTC for the component: Q17 Fuel Injector
If the condition is intermittent, wiggle the related wiring harnesses and connectors, with the ignition/vehicle on or engine running, while monitoring the scan tool circuit status parameters for the component. The parameters will display if there is a condition with the circuit or a connection.
The following conditions could cause DTC P0300 to set:
- Accessory drive bracket - Defective/Loose/Visible Damage
- Belt Driven Device - Defective/Loose/Visible Damage
- Brake Rotor - Excessive runout
- Component Malfunction - Transmission
- Drive Belt - Defective/Loose/Visible Damage
- Drive Shaft - Excessive runout
- During certain road conditions: Rough
Tire and wheel assemblies which exhibit excessive runout can produce vibrations even if the assemblies are balanced.