AutoCodes – Chevrolet – P20BB 2018 Chevrolet Silverado

P20BB 2018 Chevrolet Silverado Code - Reductant Heater 1 Control Circuit Low Voltage

Quick Answer

As reductant will freeze at temperatures below -11°C (12°F), there are 2 reductant heaters located in the reductant tank. 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: P20BB 2018 Chevrolet Silverado indicates Reductant Heater 1 Control Circuit Low Voltage.
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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 454

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 29, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P20BB 2018 Chevrolet Silverado Description

As reductant will freeze at temperatures below -11°C (12°F), there are 2 reductant heaters located in the reductant tank. One heats the reductant in the tank, and one heats the reductant supplied to the reductant injector supply pipe. The Engine Control Module (ECM) monitors the reductant temperature in the tank in order to determine if the reductant temperature is below its freeze point. If the ECM determines that the reductant may be frozen, it activates a "defrost strategy" energizing the reductant eater. This energizing action terminates when the temperature sensor measures a threshold value over which the heater must be deactivated.
The Diagnostic Trouble Code (DTC) will be set when the ECM indicates the reductant tank heater control circuit is shorted to ground or overloaded for greater than 4 s.

OBDII Code P20BB 2018 Chevrolet Silverado - Reductant Heater 1 Control Circuit Low Voltage - AutoCodes.com — P20BB 2018 Chevrolet Silverado Code - Reductant Heater 1 Control Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P20BB 2018 Chevrolet Silverado?

Faulty Reductant Heater
Reductant Heater harness is open or shorted
Reductant Heater circuit poor electrical connection
Faulty Reductant Pump and Sensor Assembly
Faulty Reductant Control Module

How to Fix the DTC P20BB 2018 Chevrolet Silverado?

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 P20BB 2018 Chevrolet Silverado 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 P20BB 2018 Chevrolet Silverado code?

Need more information on how to fix the P20BB 2018 Chevrolet Silverado code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P20BB 2018 Chevrolet Silverado code diagnosed by a professional: Find a repair shop in your area

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 P20BB 2018 Chevrolet Silverado Code

What does OBDII code P20BB mean on a 2018 Chevrolet Silverado?

P20BB indicates a low voltage issue in the control circuit for Reductant Heater 1, which is part of the Diesel Exhaust Fluid (DEF) system.

What are the symptoms of code P20BB in a 2018 Chevrolet Silverado?

Common symptoms include an illuminated check engine light, DEF system warnings, poor DEF performance, or difficulty meeting emissions standards.

What causes the P20BB code to appear?

Potential causes include a faulty reductant heater, damaged wiring or connectors in the circuit, a blown fuse, or a malfunctioning control module.

Can I still drive my 2018 Silverado with code P20BB?

While the truck may still be drivable, the DEF system may not function correctly, potentially leading to reduced performance or emissions violations.

How do I diagnose the P20BB code?

Start by checking the wiring, connectors, and fuse for the reductant heater circuit. Then test the heater's resistance and inspect the control module for faults.

How do I fix the P20BB code on my Silverado?

Repairs may involve replacing the reductant heater, repairing damaged wiring, replacing a blown fuse, or reprogramming the control module.

How much does it cost to repair code P20BB?

Repair costs vary but typically range between $150 and $500, depending on whether the issue is with the heater, wiring, or control module.

Can a faulty reductant heater cause other issues in my truck?

Yes, if the reductant heater fails, the DEF system may not work properly, leading to higher emissions or the vehicle entering a reduced power mode.

Will clearing the P20BB code with a scan tool fix the issue?

Clearing the code will only reset the check engine light temporarily. The underlying issue must be fixed to prevent the code from returning.

Is the P20BB code covered under warranty?

It may be covered under the emissions warranty, depending on the mileage and specific warranty terms of your 2018 Chevrolet Silverado. Check with your dealership.