AutoCodes – Generic – P021B

P021B 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 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 3,126

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
Comments
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Code P021B 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 - Cylinder 8 Injection Timing - AutoCodes.com — P021B Code - Cylinder 8 Injection Timing

What does this mean?

What are the Possible Causes of the DTC P021B?

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?

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 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 P021B code?

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Need Help with the Code?

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Information for Specific Makes

P021B Chevrolet — Cylinder 8 Injection Timing
P021B Dodge — Fuel Injector 8 Performance
P021B GMC — Cylinder 8 Injection Timing
P021B RAM — Fuel Injector 8 Performance

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.