P066A 2016 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 2016 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 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 P066A 2016 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 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 P066A 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 P066A 2016 GMC Sierra Code
1. What does the OBDII code P066A mean on a 2016 GMC Sierra?
P066A indicates a low voltage issue in the glow plug control circuit for cylinder 1, which helps in cold engine starts by preheating the cylinder.
2. What are the common symptoms of code P066A in a 2016 GMC Sierra?
Symptoms may include difficulty starting the engine in cold weather, rough idle, reduced fuel efficiency, and an illuminated check engine light.
3. What causes the P066A code to appear on a GMC Sierra?
Common causes include a faulty glow plug, damaged wiring or connectors in the glow plug circuit, a failed glow plug control module, or a low battery voltage issue.
4. Can I drive my 2016 GMC Sierra with a P066A code?
While driving may still be possible, it is not recommended as the engine may struggle to start in cold conditions and could lead to further damage if not repaired.
5. How do I diagnose the P066A code on my GMC Sierra?
Diagnosis involves inspecting the glow plug and its wiring for damage, testing the glow plug control module, and checking the battery voltage to ensure proper operation.
6. How do I fix the P066A code on a 2016 GMC Sierra?
Repairs may include replacing the faulty glow plug, repairing or replacing damaged wiring or connectors, or replacing the glow plug control module if it is defective.
7. How much does it cost to repair a P066A code on a GMC Sierra?
Repair costs vary but typically range from $100 to $300, depending on whether the issue involves the glow plug, wiring, or control module.
8. Can a weak battery cause the P066A code to appear?
Yes, a weak or low-voltage battery can contribute to the P066A code, as insufficient power can affect the glow plug circuit's performance.
9. How can I prevent the P066A code from returning on my GMC Sierra?
Regular maintenance, including inspecting the glow plugs, wiring, and battery, can help prevent this code from recurring.
10. Will resetting the check engine light fix the P066A code on my GMC Sierra?
Resetting the light may clear the code temporarily, but the underlying issue must be addressed to prevent the code from returning.
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