P0671 GMC Code - Cylinder 1 Glow Plug Circuit Fault
Quick Answer
n the diesel engine, air alone is compressed in the cylinder. Common causes include Faulty cylinder #1 glow plug, Cylinder #1 glow plug harness is open or shorted, Cylinder #1 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
- P0671 GMC indicates Cylinder 1 Glow Plug Circuit Fault.
- Common causes
- Common causes include Faulty cylinder #1 glow plug, Cylinder #1 glow plug harness is open or shorted, Cylinder #1 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 P0671 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 P0671 GMC?
- Faulty cylinder #1 glow plug
- Cylinder #1 glow plug harness is open or shorted
- Cylinder #1 glow plug circuit poor electrical connection
- Faulty Glow Plug Control Module (GPCM)
How to Fix the DTC P0671 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 P0671 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.
Need more information about the P0671 GMC code?
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Need Help with the Code?
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Information for Specific GMC Models
- P0671 2014 GMC Sierra — Cylinder 1 Glow Plug Circuit Fault
- P0671 2015 GMC Sierra — Cylinder 1 Glow Plug Circuit Fault
- P0671 2016 GMC Sierra — Cylinder 1 Glow Plug Circuit Fault
- P0671 2017 GMC Sierra — Cylinder 1 Glow Plug Circuit Fault
- P0671 2018 GMC Sierra — Cylinder 1 Glow Plug Circuit Fault
Frequently Asked Questions about P0671 GMC Code
1. What does the OBDII code P0671 mean on a GMC?
P0671 indicates a fault in the glow plug circuit for cylinder 1, meaning the glow plug may not be heating properly or there’s an issue with its wiring or control.
2. What are the common symptoms of a P0671 code on a GMC?
Symptoms may include difficulty starting in cold weather, rough idle, reduced fuel efficiency, or an illuminated check engine light.
3. What causes the P0671 code on a GMC?
Common causes include a faulty glow plug, damaged wiring or connectors in the glow plug circuit, a malfunctioning glow plug control module, or corrosion in the circuit.
4. Can I drive my GMC with a P0671 code?
Yes, you can drive with this code, but starting the vehicle in cold weather may be difficult, and prolonged neglect could lead to further engine issues.
5. How do I diagnose the P0671 code on a GMC?
Start by inspecting the glow plug for cylinder 1, checking for visible damage, testing the resistance with a multimeter, and examining the wiring and connectors for corrosion or breaks.
6. How do you fix the P0671 code on a GMC?
Repairs may include replacing the faulty glow plug, repairing or replacing damaged wiring, cleaning corroded connections, or replacing the glow plug control module if necessary.
7. What tools are needed to fix a P0671 code on a GMC?
You’ll typically need a multimeter, a socket set for removing the glow plug, and possibly an OBDII scanner to clear the code after repairs.
8. Can a bad glow plug cause engine damage on a GMC?
While a bad glow plug itself doesn’t usually cause engine damage, it can lead to hard starts and misfires, which may strain engine components over time.
9. How much does it cost to fix a P0671 code on a GMC?
The cost can range from $50 to $150 for a glow plug replacement, but additional repairs to the wiring or control module may increase the cost.
10. How can I prevent the P0671 code from recurring on my GMC?
Regular maintenance, including checking the glow plugs and electrical connections, can help prevent this code from recurring. Use high-quality replacement parts when necessary.
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