AutoCodes – Generic – P221F

P221F Code - Reductant Heater 3 Current Too High

Quick Answer

The Selective Catalyst Reduction (SCR) system reduces Oxides of Nitrogen (NOx) emissions by injecting a metered amount of Diesel Exhaust Fluid (DEF) or reductant into the exhaust gas stream entering the SCR catalyst. Common causes include Faulty Reductant Heater 3, Reductant Heater 3 harness is open or shorted, Reductant Heater 3 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: P221F indicates Reductant Heater 3 Current Too High.
Common causes: Common causes include Faulty Reductant Heater 3, Reductant Heater 3 harness is open or shorted, Reductant Heater 3 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 1,098

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 Sep 10, 2021

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P221F Description

The Selective Catalyst Reduction (SCR) system reduces Oxides of Nitrogen (NOx) emissions by injecting a metered amount of Diesel Exhaust Fluid (DEF) or reductant into the exhaust gas stream entering the SCR catalyst. Within the SCR catalyst, the reductant reacts with the NOx to form nitrogen, carbon dioxide, and water vapor. Upstream and downstream NOx sensors provide the Engine Control Module (ECM) with engine-out and tailpipe-out NOx levels in Parts Per Million (ppm). The ECM then adjusts the amount of reductant injected upstream of the SCR based on the NOx concentration. Engine-out NOx levels as measured by NOx Sensor 1 will either increase (high ppm) or decrease (low ppm) the amount of reductant injected. The NOx concentration as measured by NOx Sensor 2 provides the ECM with both an indication of the NOx conversion efficiency within the SCR as well as confirming the proper operation of the reductant system. The Diagnostic Trouble Code (DTC) will be set when the Glow Plug Control Module (GPCM) detects a heater short circuit by detecting a high current in the heater.

OBDII Code P221F - Reductant Heater 3 Current Too High - AutoCodes.com — P221F Code - Reductant Heater 3 Current Too High

What does this mean?

What are the Possible Causes of the DTC P221F?

Faulty Reductant Heater 3
Reductant Heater 3 harness is open or shorted
Reductant Heater 3 circuit poor electrical connection
Faulty Glow Plug Control Module (GPCM)

How to Fix the DTC P221F?

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 P221F 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 P221F code?

Need more information on how to fix the P221F code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P221F code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P221F Chevrolet — Reductant Heater 3 Current Too High
P221F GMC — Reductant Heater 3 Current Too High

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 P221F Code

1. What are the common symptoms of OBDII code P221F (Reductant Heater 3 Current Too High)?

The common symptoms of this code may include the Check Engine light illuminating on the dashboard, reduced fuel efficiency, and potential issues with the vehicle's emissions system.

2. What can cause the OBDII code P221F to trigger?

This code is typically triggered when the powertrain control module (PCM) detects that the current flowing through the Reductant Heater 3 circuit is higher than specified, indicating a potential issue with the reductant heater system.

3. How serious is the OBDII code P221F (Reductant Heater 3 Current Too High)?

While this code may not cause immediate drivability issues, it should be addressed promptly to prevent potential damage to the vehicle's emissions system and ensure proper vehicle performance.

4. How can I diagnose the cause of OBDII code P221F?

Diagnosing this code usually involves inspecting the wiring and connections related to Reductant Heater 3, testing the heater itself for proper operation, and checking the PCM for any faults or issues.

5. What are some common repair tips for fixing OBDII code P221F?

Common repair tips for this code may include repairing or replacing damaged wiring, connectors, or components in the Reductant Heater 3 circuit, as well as ensuring the reductant heater system is functioning correctly.

6. Can I drive my vehicle with the OBDII code P221F active?

It is generally not recommended to drive with this code active, as it can lead to increased emissions and potential issues with the vehicle's emissions system. It's best to address the problem as soon as possible.

7. How much does it typically cost to repair OBDII code P221F?

The cost of repairing this code can vary depending on the underlying cause of the issue, the extent of the repairs needed, and the labor rates of the repair shop. It's recommended to obtain a diagnosis and estimate from a qualified mechanic.

8. Will resetting the OBDII code P221F make it go away permanently?

Simply resetting the code may temporarily turn off the Check Engine light, but if the underlying issue is not addressed, the code is likely to return. It's important to diagnose and repair the root cause of the problem.

9. Can a DIY enthusiast fix OBDII code P221F at home?

Depending on your level of automotive experience and equipment, it may be possible to address this code at home. However, diagnosing and repairing issues related to the reductant heater system may require specialized tools and knowledge.

10. How can I prevent OBDII code P221F from coming back in the future?

Regular maintenance and inspections of the vehicle's emissions system, including the reductant heater components, can help prevent the recurrence of this code. Following the manufacturer's recommended service schedule is also advisable.