P0674 2016 GMC Sierra Code - Cylinder 4 Glow Plug Circuit Fault
Quick Answer
n the diesel engine, air alone is compressed in the cylinder. Common causes include Faulty cylinder #4 glow plug, Cylinder #4 glow plug harness is open or shorted, Cylinder #4 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
- P0674 2016 GMC Sierra indicates Cylinder 4 Glow Plug Circuit Fault.
- Common causes
- Common causes include Faulty cylinder #4 glow plug, Cylinder #4 glow plug harness is open or shorted, Cylinder #4 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 P0674 2016 GMC Sierra 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 P0674 2016 GMC Sierra?
- Faulty cylinder #4 glow plug
- Cylinder #4 glow plug harness is open or shorted
- Cylinder #4 glow plug circuit poor electrical connection
- Faulty Glow Plug Control Module (GPCM)
How to Fix the DTC P0674 2016 GMC Sierra?
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 P0674 2016 GMC Sierra 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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Frequently Asked Questions about P0674 2016 GMC Sierra Code
1. What does the OBDII code P0674 mean on a 2016 GMC Sierra?
P0674 indicates a fault in the glow plug circuit for cylinder 4, suggesting an issue with the glow plug, wiring, or related components.
2. What are the symptoms of a P0674 code on a 2016 GMC Sierra?
Common symptoms include difficulty starting the engine in cold weather, rough idling, reduced fuel efficiency, and the check engine light turning on.
3. What causes the P0674 code on a 2016 GMC Sierra?
Possible causes include a faulty glow plug for cylinder 4, damaged wiring or connectors in the glow plug circuit, a failed glow plug control module, or corrosion in the connectors.
4. Can I drive my 2016 GMC Sierra with a P0674 code?
Yes, you can drive the truck, but it may have trouble starting in cold weather, and prolonged operation without repair could lead to further damage.
5. How do I diagnose a P0674 code on a 2016 GMC Sierra?
Start by inspecting the glow plug and its wiring for cylinder 4. Use a multimeter to check for proper resistance in the glow plug and continuity in the circuit. Check for corrosion or loose connections.
6. How do I fix the P0674 code on a 2016 GMC Sierra?
Repairs may include replacing the faulty glow plug, repairing damaged wiring or connectors, or replacing the glow plug control module if necessary.
7. How much does it cost to repair a P0674 code on a 2016 GMC Sierra?
The cost can range from $50 to $150 for a glow plug replacement, plus labor costs, which may vary depending on the mechanic or dealership.
8. Can a bad glow plug cause engine damage?
A bad glow plug itself won't typically cause major engine damage, but prolonged cold starts and incomplete combustion could lead to carbon buildup and other issues.
9. What tools do I need to fix a P0674 code on a 2016 GMC Sierra?
You'll need a multimeter for testing the circuit, basic hand tools for removing and replacing the glow plug, and potentially a diagnostic scanner to clear the code.
10. How can I prevent a P0674 code from recurring on my 2016 GMC Sierra?
Regularly inspect and maintain the glow plug system, ensure connections are free of corrosion, and replace glow plugs as recommended by the manufacturer.
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