P068E GMC Code - Cylinder 8 Glow Plug Control Circuit Low Voltage
Quick Answer
n the diesel engine, air alone is compressed in the cylinder. Common causes include Faulty cylinder #8 glow plug, Cylinder #8 glow plug harness is open or shorted, Cylinder #8 glow plug circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P068E GMC indicates Cylinder 8 Glow Plug Control Circuit Low Voltage.
- Common causes
- Common causes include Faulty cylinder #8 glow plug, Cylinder #8 glow plug harness is open or shorted, Cylinder #8 glow plug circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P068E GMC Description
Control of the glow plugs is accomplished by the Glow Plug Control Module. The nominal voltage for the glow plugs is 5.4 volts. When the ignition is turned On, the Glow Plug Control Module applies 7.2 V for 2.2 s, then 5.7 V for 0.8 s, and then 5.4 V until 1200°C (2192°F) is reached. The maximum voltage of the system is 10 V. While the engine is running the voltage will vary between 4.7 - 10 V when in closed loop control to maintain a glow plug temperature that ranges from 1150° - 1180°C (2102° - 2156°F). The temperature and the power consumption are controlled between the Engine Control Module (ECM) and the Glow Plug Control Module within a wide range to suit the engine's pre-heating requirements. Each glow plug is energized individually. This capability yields more optimum heat times for the glow plugs, thus pre - glow times can be kept to a minimum for a short wait to crank times and maximum glow plug durability.
What are the Possible Causes of the DTC P068E GMC?
- Faulty cylinder #8 glow plug
- Cylinder #8 glow plug harness is open or shorted
- Cylinder #8 glow plug circuit poor electrical connection
- Faulty Glow Plug Control Module
How to Fix the DTC P068E GMC?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P068E GMC code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Information for Specific GMC Models
- P068E 2014 GMC Sierra — Cylinder 8 Glow Plug Control Circuit Low Voltage
- P068E 2015 GMC Sierra — Cylinder 8 Glow Plug Control Circuit Low Voltage
- P068E 2016 GMC Sierra — Cylinder 8 Glow Plug Control Circuit Low Voltage
- P068E 2017 GMC Sierra — Cylinder 8 Glow Plug Control Circuit Low Voltage
- P068E 2018 GMC Sierra — Cylinder 8 Glow Plug Control Circuit Low Voltage
Frequently Asked Questions about P068E GMC Code
What does OBDII code P068E mean on a GMC vehicle?
Code P068E indicates a low voltage issue in the glow plug control circuit for cylinder 8.
What are the common symptoms of code P068E in a GMC?
Symptoms may include difficulty starting the engine, rough idling, reduced engine performance, and an illuminated check engine light.
What causes code P068E in GMC vehicles?
Common causes include a faulty glow plug for cylinder 8, damaged wiring or connectors in the glow plug circuit, or a malfunctioning glow plug control module.
Can driving with code P068E cause damage to my GMC vehicle?
Driving with this code may cause starting issues and reduced performance, but long-term neglect can lead to further engine problems in diesel vehicles.
How can I diagnose code P068E on a GMC?
Use an OBDII scanner to confirm the code, inspect the glow plug control circuit wiring and connectors, and test the cylinder 8 glow plug for proper function.
What tools are needed to fix code P068E in a GMC vehicle?
You’ll typically need an OBDII scanner, a multimeter for testing voltage, and basic hand tools to replace faulty components.
How much does it cost to repair code P068E on a GMC?
Repair costs can vary but typically range from $100 to $300, depending on whether the glow plug or control module needs replacement.
Can I fix code P068E on my GMC myself?
If you have experience with basic vehicle repairs, you can inspect the wiring, test the glow plug, and replace components as needed.
How do I prevent code P068E from occurring again?
Regular maintenance, such as inspecting the glow plug system and replacing worn components, can help prevent recurrence.
What is the role of a glow plug in GMC diesel engines?
Glow plugs heat the air in the combustion chamber to aid engine starting in cold conditions, especially in diesel engines.
Discuss the causes and fixes for P068E GMC OBDII Code
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