AutoCodes – RAM – P20B4 RAM

P20B4 RAM Code - Diesel Exhaust Fluid Reductant Heater Control Valve Circuit High

Quick Answer

The Diesel Exhaust Fluid (DEF) Tank Level Sensor and Diesel Exhaust Fluid (DEF) Tank Temperature Sensor are a combination sensor used to measure the level and temperature of the fluid in the DEF Tank. Common causes include Faulty Diesel Exhaust Fluid Reductant Heater Control Valve, Diesel Exhaust Fluid Reductant Heater Control Valve harness is open or shorted, Diesel Exhaust Fluid Reductant Heater Control Valve 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: P20B4 RAM indicates Diesel Exhaust Fluid Reductant Heater Control Valve Circuit High.
Common causes: Common causes include Faulty Diesel Exhaust Fluid Reductant Heater Control Valve, Diesel Exhaust Fluid Reductant Heater Control Valve harness is open or shorted, Diesel Exhaust Fluid Reductant Heater Control Valve 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 139

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 Jul 15, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P20B4 RAM Description

The Diesel Exhaust Fluid (DEF) Tank Level Sensor and Diesel Exhaust Fluid (DEF) Tank Temperature Sensor are a combination sensor used to measure the level and temperature of the fluid in the DEF Tank. Though combined, the level sensor and the temperature sensor operate independently of each other. Both sensors operate as a two-wire 5-Volt sensor. The DEF Tank Level Sensor is a 14-point magnetic reed switch sensor. The DEF Tank Temperature Sensor is a negative temperature coefficient sensor. The DEF Dosing Control Unit will illuminate the MIL lamp via the Powertrain Control Module (PCM) immediately after this diagnostic runs and fails. The DEF Dosing Control Unit will turn off the MIL lamp via the PCM immediately after the diagnostic runs and passes in three consecutive key cycles. This monitor runs a short time after Diesel Exhaust Fluid Tank heating is commanded. The Diagnostic Trouble Code (DTC) will be set when the DEF Dosing Control Unit detects a Diesel Exhaust Fluid Reductant Heater Control Valve circuit high.

OBDII Code P20B4 RAM - Diesel Exhaust Fluid Reductant Heater Control Valve Circuit High - AutoCodes.com — P20B4 RAM Code - Diesel Exhaust Fluid Reductant Heater Control Valve Circuit High

What does this mean?

What are the Possible Causes of the DTC P20B4 RAM?

Faulty Diesel Exhaust Fluid Reductant Heater Control Valve
Diesel Exhaust Fluid Reductant Heater Control Valve harness is open or shorted
Diesel Exhaust Fluid Reductant Heater Control Valve circuit poor electrical connection

How to Fix the DTC P20B4 RAM?

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 P20B4 RAM 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.

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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.