AutoCodes – GMC – P021B 2018 GMC Sierra

P021B 2018 GMC Sierra Code - Cylinder 8 Injection Timing

Quick Answer

The Engine Control Module (ECM) has the ability to learn injector timing performance. Common causes include Faulty Fuel Injector 8, Fuel Injector 8 harness is open or shorted, Fuel Injector 8 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: P021B 2018 GMC Sierra indicates Cylinder 8 Injection Timing.
Common causes: Common causes include Faulty Fuel Injector 8, Fuel Injector 8 harness is open or shorted, Fuel Injector 8 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.

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Code Popularity 198

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 22, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P021B 2018 GMC Sierra Description

The Engine Control Module (ECM) has the ability to learn injector timing performance. When the engine is at operating temperature, throttle closed and in deceleration fuel cut-off mode, the ECM will pulse each injector individually and measure the changes in rotational speed of the crankshaft using the input from the crankshaft position sensor. The ECM will run this diagnostic at one fuel rail pressure operating point for each injector. The ECM stores the injector timing value. The Diagnostic Trouble Code (DTC) will be set when the time to build up sufficient current to open the injector is below or above a predetermined threshold.

OBDII Code P021B 2018 GMC Sierra - Cylinder 8 Injection Timing - AutoCodes.com — P021B 2018 GMC Sierra Code - Cylinder 8 Injection Timing

What does this mean?

What are the Possible Causes of the DTC P021B 2018 GMC Sierra?

Faulty Fuel Injector 8
Fuel Injector 8 harness is open or shorted
Fuel Injector 8 circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P021B 2018 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 P021B 2018 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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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 P021B 2018 GMC Sierra Code

1. What does the OBDII code P021B mean on a 2018 GMC Sierra?

- Code P021B indicates a problem with the injection timing in Cylinder 8, suggesting that the fuel is not being injected into the cylinder at the correct point in the engine cycle.

2. What are common symptoms of the P021B code in a 2018 GMC Sierra?

- Symptoms can include a rough running engine, reduced fuel efficiency, engine misfire, and the check engine light turning on.

3. What can cause the P021B code to appear on a 2018 GMC Sierra?

- Possible causes include issues with the fuel injector itself (such as clogging or failure), problems with the wiring or connectors leading to the injector, or a faulty engine control module (ECM).

4. How can I diagnose the P021B code in my 2018 GMC Sierra?

- Diagnosis should start with reading the engine codes using an OBDII scanner, checking for additional codes, and inspecting the wiring and connectors. Testing the fuel injector operation for Cylinder 8 and verifying the timing with professional diagnostic equipment is also crucial.

5. What are the steps to fix the P021B code on a 2018 GMC Sierra?

- Repairs may involve cleaning or replacing the faulty fuel injector, repairing or replacing damaged wiring, or, in some cases, updating or replacing the ECM if it is found to be defective.

6. Is it safe to drive a 2018 GMC Sierra with the P021B code?

- While you might be able to drive for a short period, it is not advisable as the underlying issue can lead to more serious engine problems or decreased vehicle performance.

7. How urgent is it to address the P021B code in a 2018 GMC Sierra?

- It is fairly urgent to address this issue to prevent further engine damage or performance issues. It is recommended to repair this as soon as possible.

8. What tools are needed to confirm the P021B code on a 2018 GMC Sierra?

- You will need an OBDII scanner to read the code and a multimeter to check the injector's electrical connections. A fuel pressure gauge and a diagnostic scanner with real-time data capabilities might also be necessary for deeper analysis.

9. Could the P021B code be triggered by poor fuel quality in a 2018 GMC Sierra?

- Yes, poor fuel quality can contribute to injector problems by causing clogging or damage, which might set off the P021B code. Regularly using high-quality fuel can prevent such issues.

10. What is the cost range for repairing the P021B code on a 2018 GMC Sierra?

- The cost can vary widely depending on the nature of the problem. Simple fixes like cleaning an injector might be under $100, whereas replacing a faulty ECM or injector could cost several hundred dollars, not including labor.