Engine-CodesGMC – P135B 2018 GMC Sierra

P135B 2018 GMC Sierra Code - Ignition Coil Supply Voltage Circuit Bank 2

Quick Answer

The P135B diagnostic trouble code (DTC) for a 2018 GMC Sierra relates to the Ignition Coil Supply Voltage Circuit Bank 2. Common causes include Faulty ignition coil in Bank 2, Damaged wiring or connectors in the ignition coil circuit, Malfunctioning engine control module (ECM). 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
P135B 2018 GMC Sierra indicates Ignition Coil Supply Voltage Circuit Bank 2.
Common causes
Common causes include Faulty ignition coil in Bank 2, Damaged wiring or connectors in the ignition coil circuit, Malfunctioning engine control module (ECM).
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.
Table of contents Created and updated by William Orellana on Sep 19, 2024
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Code P135B 2018 GMC Sierra Description

The P135B diagnostic trouble code (DTC) for a 2018 GMC Sierra relates to the Ignition Coil Supply Voltage Circuit Bank 2. This code indicates that there is a problem with the supply voltage to the ignition coil in the second bank of cylinders in the engine. The ignition coil is a crucial component in the ignition system, responsible for converting the low voltage from the battery into the high voltage needed to create a spark in the spark plugs. This spark is essential for igniting the air-fuel mixture in the combustion chamber, which powers the engine.

OBDII Code P135B 2018 GMC Sierra - Ignition Coil Supply Voltage Circuit Bank 2
P135B 2018 GMC Sierra Code - Ignition Coil Supply Voltage Circuit Bank 2

Common Causes of P135B 2018 GMC Sierra

  1. Faulty ignition coil in Bank 2
  2. Damaged wiring or connectors in the ignition coil circuit
  3. Malfunctioning engine control module (ECM)
  4. Issues with the power supply to the ignition system

Symptoms of P135B 2018 GMC Sierra

  1. Engine misfires or rough idling
  2. Decreased acceleration and overall performance
  3. Illumination of the Check Engine Light
  4. Reduced fuel efficiency

How to Fix P135B 2018 GMC Sierra

  1. Begin by diagnosing the specific cause of the issue using a scan tool to pinpoint the exact problem within the ignition coil supply voltage circuit.
  2. Inspect the ignition coil in Bank 2 for any signs of damage or malfunction. Replace the ignition coil if necessary.
  3. Check the wiring and connectors in the ignition coil circuit for any breaks, corrosion, or loose connections. Repair or replace as needed.
  4. Test the engine control module (ECM) to ensure it is functioning correctly. Replace the ECM if it is found to be faulty.
  5. Verify the power supply to the ignition system to ensure it is delivering the correct voltage. Address any issues with the power supply as required.

Cost to Fix P135B 2018 GMC Sierra

The typical repair costs for addressing the P135B code on a 2018 GMC Sierra can vary depending on the specific cause of the issue and the extent of the repairs needed. In general, the cost of replacing an ignition coil can range from $100 to $300, while addressing wiring or connector issues may add to the total cost. The labor costs for diagnosing and repairing this problem can range from $150 to $400, depending on the shop's hourly rates and the complexity of the repair. It's advisable to consult with a trusted mechanic or auto repair shop to get a more accurate estimate based on the specific circumstances of your vehicle.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P135B 2018 GMC Sierra Code

1. What does the OBDII code P135B mean on a 2018 GMC Sierra?

P135B indicates an issue in the ignition coil supply voltage circuit for Bank 2, which affects the proper functioning of the ignition system.

2. What are the common symptoms of code P135B in a 2018 GMC Sierra?

Common symptoms include engine misfires, rough idling, reduced engine performance, hesitation during acceleration, and the Check Engine Light turning on.

3. What causes the P135B code to appear?

The most common causes include a faulty ignition coil, damaged wiring or connectors in the ignition coil circuit, a failing Powertrain Control Module (PCM), or voltage supply issues.

4. How can I diagnose the P135B code on my 2018 GMC Sierra?

Start by inspecting the ignition coil for Bank 2, checking for damaged wiring or loose connections, and testing the voltage supply to the coil. A scan tool can also help monitor live data and pinpoint the issue.

5. Can I drive my 2018 GMC Sierra with the P135B code active?

It's not recommended to drive with this code active, as it can cause engine misfires, reduced performance, and potential damage to other engine components over time.

6. How do I fix the P135B code on a 2018 GMC Sierra?

Repairs may include replacing the faulty ignition coil, repairing or replacing damaged wiring, cleaning or securing electrical connectors, and, in rare cases, reprogramming or replacing the PCM.

7. How do I identify which ignition coil is on Bank 2 for the P135B code?

Bank 2 refers to the side of the engine opposite Bank 1, which typically contains cylinder 1. Consult your vehicle’s service manual or cylinder layout diagram for precise identification.

8. Can a weak battery cause the P135B code to appear?

Yes, a weak or failing battery can cause voltage supply issues, potentially triggering the P135B code.

9. What tools are needed to troubleshoot the P135B code on a 2018 GMC Sierra?

You’ll need an OBDII scan tool, a multimeter for voltage testing, and possibly a wiring diagram for the ignition coil circuit.

10. Is a P135B code specific to GM vehicles like the 2018 GMC Sierra?

Yes, the P135B code is manufacturer-specific to GM vehicles and relates to the ignition coil supply voltage circuit on Bank 2.

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