AutoCodes – Generic – P221E

P221E Code - Reductant Heater 3 Current Too Low

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: P221E indicates Reductant Heater 3 Current Too Low.
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 1,885

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 P221E 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 open circuit by detecting a low current in the heater.

OBDII Code P221E - Reductant Heater 3 Current Too Low - AutoCodes.com — P221E Code - Reductant Heater 3 Current Too Low

What does this mean?

What are the Possible Causes of the DTC P221E?

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 P221E?

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 P221E 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 P221E code?

Need more information on how to fix the P221E code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P221E code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P221E Chevrolet — Reductant Heater 3 Current Too Low
P221E GMC — Reductant Heater 3 Current Too Low

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 P221E Code

1. What does the OBDII code P221E mean?

P221E indicates that the reductant heater 3, part of the diesel exhaust fluid (DEF) system, has a current that is too low, which could impact the proper operation of the DEF system.

2. What are the common symptoms of P221E?

Symptoms may include the check engine light turning on, poor DEF system performance, reduced fuel efficiency, or the vehicle entering limp mode.

3. What causes the P221E code?

Common causes include a faulty reductant heater, damaged wiring or connectors in the reductant heater circuit, a blown fuse, or a failing powertrain control module (PCM).

4. Can I drive with the P221E code?

While you may be able to drive the vehicle, prolonged operation with this code can lead to DEF system issues and potential engine performance problems. Itâ€™s best to address the issue promptly.

5. How is P221E diagnosed?

A technician will use a scan tool to confirm the code, inspect the reductant heater and its wiring, check for blown fuses, and test the heaterâ€™s resistance and current draw.

6. How do you fix the P221E code?

Repairs may include replacing the reductant heater, repairing or replacing damaged wiring or connectors, replacing a blown fuse, or reprogramming or replacing the PCM if necessary.

7. What tools are needed to fix P221E?

Common tools include a diagnostic scan tool, multimeter, and basic hand tools for inspecting and repairing the DEF system components.

8. How much does it cost to fix the P221E code?

Repair costs vary depending on the issue but may range from $100 to $500, with heater replacement being on the higher end.

9. Can a faulty reductant heater damage the engine?

A faulty reductant heater itself wonâ€™t directly damage the engine, but it can lead to improper DEF dosing and emissions problems, which might trigger limp mode or other performance issues.

10. Is P221E specific to certain vehicle brands?

P221E is commonly found in diesel vehicles equipped with DEF systems, including models from Ford, GM, Dodge, and others. Check your vehicleâ€™s service manual for specific details.