P066A 2017 GMC Sierra Code - Cylinder 1 Glow Plug Control Circuit Low 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
- P066A 2017 GMC Sierra indicates Cylinder 1 Glow Plug Control Circuit Low 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 P066A 2017 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 P066A 2017 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 P066A 2017 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 P066A 2017 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 P066A 2017 GMC Sierra Code
1. What does the OBD-II code P066A mean on a 2017 GMC Sierra?
The code P066A indicates a low voltage issue in the Cylinder 1 Glow Plug Control Circuit, which is responsible for preheating the diesel engine for combustion.
2. What are the common symptoms of code P066A in a 2017 GMC Sierra?
Symptoms include difficulty starting the engine in cold weather, reduced fuel efficiency, rough idling, and possible illumination of the check engine light.
3. What causes the P066A code to appear in a 2017 GMC Sierra?
Common causes include a faulty glow plug, damaged wiring or connections in the glow plug circuit, a bad glow plug control module, or a weak battery.
4. How do I diagnose the P066A code on my 2017 GMC Sierra?
Start by inspecting the glow plug and its wiring for damage or corrosion. Use a multimeter to test the glow plug’s resistance and check the voltage at the control module.
5. Can I drive my 2017 GMC Sierra with the P066A code active?
Driving is possible but not recommended, especially in cold weather, as the engine may struggle to start and could experience reduced performance.
6. How do I fix the P066A code on my 2017 GMC Sierra?
Repairs may include replacing the faulty glow plug, repairing damaged wiring, cleaning corroded connections, or replacing the glow plug control module.
7. How much does it cost to repair the P066A code on a 2017 GMC Sierra?
The cost varies but typically ranges from $100 to $300 for parts and labor, depending on whether the glow plug, wiring, or control module needs replacement.
8. Can a weak battery cause the P066A code on a 2017 GMC Sierra?
Yes, a weak or failing battery can lead to insufficient voltage in the glow plug circuit and trigger the P066A code.
9. How can I prevent the P066A code from recurring in my 2017 GMC Sierra?
Regularly inspect and maintain the glow plugs, wiring, and battery. Address any starting issues or electrical problems as soon as they arise.
10. Will clearing the P066A code without repairs fix my 2017 GMC Sierra?
Clearing the code without addressing the root cause will not fix the issue, and the code is likely to return after a short time.
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