AutoCodes – RAM – P20B5 RAM

P20B5 RAM Code - Diesel Exhaust Fluid Reductant Pump Heater Control Circuit Open

Quick Answer

The Diesel Exhaust Fluid (DEF) Supply Pump Assembly has an internal heater to prevent the fluid from freezing inside the pump. Common causes include Faulty Diesel Exhaust Fluid (DEF) Supply Pump Assembly, Diesel Exhaust Fluid Supply Pump Assembly harness is open or shorted, Diesel Exhaust Fluid Supply Pump Assembly 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: P20B5 RAM indicates Diesel Exhaust Fluid Reductant Pump Heater Control Circuit Open.
Common causes: Common causes include Faulty Diesel Exhaust Fluid (DEF) Supply Pump Assembly, Diesel Exhaust Fluid Supply Pump Assembly harness is open or shorted, Diesel Exhaust Fluid Supply Pump Assembly 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 192

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 P20B5 RAM Description

The Diesel Exhaust Fluid (DEF) Supply Pump Assembly has an internal heater to prevent the fluid from freezing inside the pump. The power supply and control circuits are controlled by the DEF Dosing Control Unit. The DEF Supply Pump Heater is integrated into the DEF Supply Pump Assembly and is not serviced separately. The DEF Dosing Control Unit will illuminate the MIL light via the Powertrain Control Module (PCM) immediately after the diagnostics runs and fails and the line heater will be disabled. The DEF Dosing Control Unit will turn off the MIL light via the PCM when the monitor runs and passes in three consecutive key cycles. The Diagnostic Trouble Code (DTC) will be set when the DEF Dosing Control Unit detects that the DEF Supply Pump heater circuit is open or shorted to ground.

OBDII Code P20B5 RAM - Diesel Exhaust Fluid Reductant Pump Heater Control Circuit Open - AutoCodes.com — P20B5 RAM Code - Diesel Exhaust Fluid Reductant Pump Heater Control Circuit Open

What does this mean?

What are the Possible Causes of the DTC P20B5 RAM?

Faulty Diesel Exhaust Fluid (DEF) Supply Pump Assembly
Diesel Exhaust Fluid Supply Pump Assembly harness is open or shorted
Diesel Exhaust Fluid Supply Pump Assembly circuit poor electrical connection
Faulty Diesel Exhaust Fluid Dosing Control Unit

How to Fix the DTC P20B5 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 P20B5 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.