P0676 GMC Code - Cylinder 6 Glow Plug Circuit Fault
Quick Answer
n the diesel engine, air alone is compressed in the cylinder. Common causes include Faulty cylinder #6 glow plug, Cylinder #6 glow plug harness is open or shorted, Cylinder #6 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
- P0676 GMC indicates Cylinder 6 Glow Plug Circuit Fault.
- Common causes
- Common causes include Faulty cylinder #6 glow plug, Cylinder #6 glow plug harness is open or shorted, Cylinder #6 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 P0676 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 P0676 GMC?
- Faulty cylinder #6 glow plug
- Cylinder #6 glow plug harness is open or shorted
- Cylinder #6 glow plug circuit poor electrical connection
- Faulty Glow Plug Control Module (GPCM)
How to Fix the DTC P0676 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 P0676 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
- P0676 2014 GMC Sierra — Cylinder 6 Glow Plug Circuit Fault
- P0676 2015 GMC Sierra — Cylinder 6 Glow Plug Circuit Fault
- P0676 2016 GMC Sierra — Cylinder 6 Glow Plug Circuit Fault
- P0676 2017 GMC Sierra — Cylinder 6 Glow Plug Circuit Fault
- P0676 2018 GMC Sierra — Cylinder 6 Glow Plug Circuit Fault
Frequently Asked Questions about P0676 GMC Code
What does the OBDII code P0676 mean for a GMC vehicle?
P0676 indicates a Cylinder 6 Glow Plug Circuit Fault, meaning the engine control module (ECM) has detected an issue with the glow plug or its electrical circuit for cylinder 6.
What are the common symptoms of a P0676 code?
Symptoms may include difficulty starting the engine in cold weather, rough idling, reduced fuel efficiency, and the check engine light illuminating.
What causes a P0676 code to appear?
Common causes include a faulty glow plug, damaged wiring or connectors in the cylinder 6 glow plug circuit, a failed glow plug control module, or corrosion at electrical connections.
How can I diagnose the P0676 code?
Start by visually inspecting the wiring and connectors for damage or corrosion. Use a multimeter to test the glow plug resistance and check for proper voltage in the circuit. A diagnostic scan tool can also help pinpoint the issue.
Can I drive my GMC with a P0676 code?
While the vehicle may still run, driving with this code can lead to poor cold-weather performance and potential engine damage, so it’s best to address the issue promptly.
How do I fix the P0676 code?
Repairs may include replacing the faulty glow plug, repairing damaged wiring or connectors, cleaning corroded connections, or replacing the glow plug control module if necessary.
How much does it cost to fix a P0676 code?
The cost varies depending on the repair, but replacing a single glow plug typically costs between $100 and $300, including parts and labor.
Can I reset the P0676 code without fixing the problem?
You can clear the code with a scan tool, but if the underlying issue isn’t resolved, the code will likely reappear.
How can I prevent the P0676 code from occurring?
Routine maintenance, such as inspecting and cleaning electrical connectors and replacing glow plugs as needed, can help prevent this issue.
Is the P0676 code specific to GMC vehicles?
No, P0676 is a generic OBDII code applicable to various diesel vehicles, but the troubleshooting steps and repairs may vary slightly by make and model.
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