GM GENUINE PARTS Glow Plug 68G (12690238) for Chevrolet/Buick/GMC/Cadillac — GN-type self-regulating, fast-heat OEM fit

GM Genuine Parts 68G (12690238) glow plug is an OEM-quality diesel engine heating element engineered to provide reliable cold-start assistance by delivering controlled heat to the combustion chamber.

Designed and validated by GM engineers, this glow plug uses a GN-type self-regulating coil to heat faster at low temperatures and limit current as it warms. It matches original equipment fitment and reach options, so it installs like the part your Chevrolet, Buick, GMC, or Cadillac was built with. The construction and testing standards reflect General Motors' service-part specifications for durability and consistent performance across a wide range of diesel applications.

How does this glow plug improve cold starts?

The GN-type regulating coil heats rapidly to help raise combustion-chamber temperature before fuel injection, which reduces rough cranking and white smoke during initial starts. Its self-regulating behavior prevents excessive current draw as temperature rises, helping preserve battery life and electrical components.

• GN-type coil for fast initial heat
• Self-regulating to avoid overheating and excess battery drain
• Engineered to meet GM OE electrical and thermal tolerances

Will this fit my diesel vehicle and how do I choose the right reach?

GM provides a range of reach lengths—21 mm to 40 mm—so technicians can match the glow plug to the combustion-chamber depth and OEM specification for each engine. Using the correct reach ensures proper heat placement and avoids interference with piston motion or chamber geometry.

• Available reaches from 21 mm to 40 mm to match chamber requirements
• Direct-replacement design for compatible Chevrolet, Buick, GMC, and Cadillac diesels
• Check your vehicle's factory service manual or parts lookup for exact 12690238 fitment

How reliable and durable is the GM Genuine Parts glow plug?

These glow plugs are manufactured to GM's production and service standards and undergo validation by GM engineers to ensure consistent operation under typical driving conditions. Materials and coil design are selected to withstand repeated thermal cycles and electrical loads associated with diesel starting routines.

• Built and tested to General Motors’ engineering standards
• Materials and coil design resist thermal fatigue and corrosion
• Some GM Genuine Parts may have formerly appeared as ACDelco GM Original Equipment

What should technicians expect during installation and maintenance?

Installation follows standard glow-plug replacement procedures: disconnect battery, remove wiring harness, extract the old plug, and torque the new plug to factory specification. Inspect the cylinder head port for carbon buildup and confirm electrical connection integrity to ensure consistent heating performance.

• Install like an OE replacement—follow factory torque and wiring procedures
• Inspect and clean glow-plug bore and connector contacts before assembly
• Verify electrical supply and relay/function after installation

Who is this for: The GM Genuine Parts 68G (12690238) glow plug is intended for owners, fleets, and technicians who require an OEM-spec replacement for diesel engines in Chevrolet, Buick, GMC, or Cadillac models. It’s a practical choice for anyone seeking direct-fit, GM-validated components that match the vehicle’s original design, especially in colder climates or for vehicles showing rough cold starts or reduced preheat performance.