P066B 2014 GMC Sierra Code - Cylinder 1 Glow Plug Control Circuit High Voltage
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
- P066B 2014 GMC Sierra indicates Cylinder 1 Glow Plug Control Circuit High Voltage.
- 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 P066B 2014 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 P066B 2014 GMC Sierra?
- 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
How to Fix the DTC P066B 2014 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 P066B 2014 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 P066B 2014 GMC Sierra Code
1. What does the OBDII code P066B mean on a 2014 GMC Sierra?
The P066B code indicates a high voltage issue in the glow plug control circuit for cylinder 1, which affects the engine's starting and warming process in cold conditions.
2. What are the common symptoms of the P066B code on a 2014 GMC Sierra?
Symptoms may include difficulty starting the engine in cold weather, poor fuel efficiency, rough idling, and an illuminated check engine light.
3. What causes the P066B code to appear on a 2014 GMC Sierra?
Possible causes include a faulty glow plug, damaged wiring or connectors in the cylinder 1 glow plug circuit, a defective glow plug control module, or a short or open circuit.
4. Can I drive my 2014 GMC Sierra with the P066B code?
While the truck may be drivable, it could experience starting issues in cold weather and reduced performance. It’s best to address the issue promptly to avoid further damage.
5. How do I diagnose the P066B code on a 2014 GMC Sierra?
Diagnosis involves inspecting the glow plug for cylinder 1, checking the wiring and connectors for damage, and testing the glow plug control module for proper operation.
6. How can I fix the P066B code on my 2014 GMC Sierra?
Repairs may include replacing the faulty glow plug, repairing or replacing damaged wiring, or replacing the glow plug control module if it is defective.
7. How much does it cost to repair the P066B code on a 2014 GMC Sierra?
The repair cost can range from $100 to $500 depending on whether you need a new glow plug, wiring repair, or a replacement control module.
8. Can a bad glow plug cause engine damage on a 2014 GMC Sierra?
A bad glow plug itself won’t directly damage the engine, but prolonged issues with starting or incomplete combustion can lead to other engine problems over time.
9. How do I prevent the P066B code from returning on my 2014 GMC Sierra?
Regularly inspect and maintain the glow plugs, wiring, and control module, especially before colder weather, to prevent circuit issues.
10. Will a P066B code cause my 2014 GMC Sierra to fail an emissions test?
It might, as a malfunctioning glow plug can lead to incomplete combustion and increased emissions, which could fail the test.
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