AutoCodes – GMC – P021A GMC

P021A GMC Code - Cylinder 7 Injection Timing

Quick Answer

The Engine Control Module (ECM) has the ability to learn injector timing performance. Common causes include Faulty Fuel Injector 7, Fuel Injector 7 harness is open or shorted, Fuel Injector 7 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: P021A GMC indicates Cylinder 7 Injection Timing.
Common causes: Common causes include Faulty Fuel Injector 7, Fuel Injector 7 harness is open or shorted, Fuel Injector 7 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 392

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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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 P021A GMC 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 P021A GMC - Cylinder 7 Injection Timing - AutoCodes.com — P021A GMC Code - Cylinder 7 Injection Timing

What does this mean?

What are the Possible Causes of the DTC P021A GMC?

Faulty Fuel Injector 7
Fuel Injector 7 harness is open or shorted
Fuel Injector 7 circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P021A GMC?

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 P021A GMC 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.

Need more information about the P021A GMC code?

Need more information on how to fix the P021A GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P021A GMC code diagnosed by a professional: Find a repair shop in your area

Information for Specific GMC Models

P021A 2014 GMC Sierra — Cylinder 7 Injection Timing
P021A 2015 GMC Sierra — Cylinder 7 Injection Timing
P021A 2016 GMC Sierra — Cylinder 7 Injection Timing
P021A 2017 GMC Sierra — Cylinder 7 Injection Timing
P021A 2018 GMC Sierra — Cylinder 7 Injection Timing

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 P021A GMC Code

What does the OBD-II code P021A mean on a GMC?

P021A indicates an issue with the injection timing for cylinder 7, which may result from a malfunction in the fuel injection system or timing control components.

What are common symptoms of the P021A code on a GMC?

Symptoms may include rough idling, engine misfires, reduced fuel efficiency, increased emissions, and possibly a check engine light.

What causes the P021A code on a GMC?

Common causes include a faulty fuel injector for cylinder 7, wiring or connection issues, a malfunctioning ECM, or problems with the timing control system.

Can driving a GMC with the P021A code cause damage?

Yes, driving with this code can lead to engine damage, increased emissions, or further issues with the fuel injection system if not promptly addressed.

How is the P021A code diagnosed on a GMC?

A mechanic will use an OBD-II scanner, inspect cylinder 7â€™s fuel injector and wiring, check timing control components, and test the ECM for proper operation.

How can the P021A code on a GMC be fixed?

Repairs may include replacing the fuel injector for cylinder 7, repairing wiring connections, recalibrating timing, or replacing the ECM if necessary.

How much does it cost to repair the P021A code on a GMC?

Repair costs vary, but replacing a fuel injector typically costs $200-$400, while ECM replacement can exceed $500, depending on labor and parts.

Can a dirty fuel injector cause the P021A code on a GMC?

Yes, a clogged or dirty fuel injector can disrupt injection timing for cylinder 7, triggering the P021A code.

Is the P021A code specific to GMC vehicles?

No, the code applies to vehicles with OBD-II systems, but the troubleshooting and repair process may vary by make and model.

Should I clear the P021A code on a GMC without repairs?

Clearing the code without addressing the issue may temporarily turn off the check engine light but wonâ€™t fix the underlying problem, which could worsen over time.