Fix P20BB: STEP-BY-STEP diagnostic GUIDE!

The P20BB: Reductant Heater ‘A’ Control Circuit Low refers to a situation where the control circuit for the reductant heater ‘A’ is experiencing lower-than-expected voltage. This could point to issues in the electrical circuit, a faulty heater, or a problem with the control module.

P20BB – Quick Overview

CodeInformation
MeaningP20BB: Reductant Heater ‘A’ Control Circuit Low
Is it serious?Yes, this can cause the reductant system to malfunction, leading to improper emissions management.
Possible causes– Low voltage in the reductant heater ‘A’ control circuit
– Faulty heater
– Faulty control module
How to diagnose?– Measure voltage in the heater control circuit
– Test reductant heater ‘A’
– Check the control module functionality

P20BB Meaning

The P20BB fault code indicates that the control circuit for reductant heater ‘A’ is receiving insufficient voltage. This can affect the heater’s performance, which is crucial for the reductant system’s proper function in reducing emissions. Low voltage may be caused by wiring issues, a defective heater, or problems with the control module that governs the heater.

Step-by-step diagnostic guide

ActionDescriptionTools Needed
Check for Other CodesUse an OBD-II scanner to identify any other related codes that could help diagnose the issue.OBD-II Scanner
Measure Voltage in the Heater Control CircuitUse a multimeter to measure the voltage in the control circuit for reductant heater ‘A’ and confirm it is within the specified range.Multimeter
Test Reductant Heater ‘A’Use a diagnostic tool to check the functionality of reductant heater ‘A’ and ensure it is working as expected.Multimeter, Diagnostic Tool
Inspect the Control ModuleVerify the control module’s operation to ensure it is functioning properly and not causing the low voltage issue.Diagnostic Tool
Repair or Replace Wiring/HeaterIf low voltage is detected, inspect wiring for shorts or disconnections and repair or replace reductant heater ‘A’ if necessary.Wiring Kit, Replacement Heater
Clear the Code and Test DriveAfter making repairs, clear the code using an OBD-II scanner and test drive the vehicle to confirm that the issue is resolved.OBD-II Scanner, Vehicle Manual
Recheck for CodesAfter the test drive, rescan the vehicle to ensure the P20BB code does not reappear.OBD-II Scanner
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