AutoCodes – Generic – P20C4

P20C4 Code - Reductant Heater 'C' Control Circuit High

Quick Answer

The reductant heater and sender assembly contains pickup tube for reductant pump module, an electric heating element, a reductant temperature sensor and an electrode type level sensor. Common causes include Faulty Reductant Heater, Reductant Heater harness is open or shorted, Reductant Heater 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: P20C4 indicates Reductant Heater 'C' Control Circuit High.
Common causes: Common causes include Faulty Reductant Heater, Reductant Heater harness is open or shorted, Reductant Heater 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 8,802

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 Jun 14, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P20C4 Description

The reductant heater and sender assembly contains pickup tube for reductant pump module, an electric heating element, a reductant temperature sensor and an electrode type level sensor. The heating element is directly above pickup tubes inlet filter. When reductant temperature sensor detects the diesel exhaust fluid temperature dropping to the freezing point of 12Â°F (-11Â°C), the Powertrain Control Module (PCM) will command the glow plug control module to provide voltage to heating element. The heating element thaws liquid reductant within reductant heater and sender assembly reservoir during cold ambient temperatures.

OBDII Code P20C4 - Reductant Heater 'C' Control Circuit High - AutoCodes.com — P20C4 Code - Reductant Heater 'C' Control Circuit High

What does this mean?

What are the Possible Causes of the DTC P20C4?

Faulty Reductant Heater
Reductant Heater harness is open or shorted
Reductant Heater circuit poor electrical connection

How to Fix the DTC P20C4?

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 P20C4 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 P20C4 code?

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Information for Specific Makes

P20C4 Chevrolet — Reductant Heater 'C' Control Circuit High
P20C4 Ford — Reductant Heater 'C' Control Circuit High
P20C4 GMC — Reductant Heater 'C' Control Circuit 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.