P20BB RAM Code - Reductant Heater 'A' Control Circuit Low
Quick Answer
The Powertrain Control Module (PCM) controls the Diesel Exhaust Fluid (DEF) Heaters via datalink communication with the Diesel Exhaust Fluid Dosing Control Unit (DEF DCU - sometimes referred to as the Selective Catalytic Reduction (SCR) Module). Common causes include Faulty Diesel Exhaust Fluid (DEF) Pressure Line heater, DEF Pressure Line heater harness is open or shorted, DEF Pressure Line 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 RAM indicates Reductant Heater 'A' Control Circuit Low.
- Common causes
- Common causes include Faulty Diesel Exhaust Fluid (DEF) Pressure Line heater, DEF Pressure Line heater harness is open or shorted, DEF Pressure Line 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.
Code P20BB RAM Description
Activation of the DEF Supply Line and DEF Tank Heaters operate independently of each other. Line heating is based on the Ambient Temperature Sensor input and Tank heating is based on the DEF Tank Temperature Sensor value. Heating of the Line or Tank Heater is initiated when the corresponding temperature value is below -5°C (23°F). Heating stops when the corresponding temperature value goes above -4°C (24.8°F). The DEF Dosing Control Unit monitors these inputs and reports them to the Powertrain Control Module (PCM). The PCM will illuminate the MIL lamp after this diagnostic runs and fails. The PCM will turn off the MIL light 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 Pressure Line heater circuit voltage is below a calibrated threshold.
What are the Possible Causes of the DTC P20BB RAM?
- Faulty Diesel Exhaust Fluid (DEF) Pressure Line heater
- DEF Pressure Line heater harness is open or shorted
- DEF Pressure Line heater circuit poor electrical connection
- Faulty Diesel Exhaust Fluid Dosing Control Unit (DEF DCU)
How to Fix the DTC P20BB 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 P20BB 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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Frequently Asked Questions about P20BB RAM Code
1. What are the common symptoms of OBDII code P20BB RAM (Reductant Heater 'A' Control Circuit Low)?
- Common symptoms may include the Check Engine Light illuminating, reduced engine performance, and potential issues with the vehicle's emissions system.
2. What are the possible causes of OBDII code P20BB RAM?
- The code P20BB RAM can be triggered by issues such as a faulty reductant heater 'A', damaged wiring or connectors in the control circuit, or a problem with the powertrain control module (PCM).
3. How can I diagnose the cause of OBDII code P20BB RAM?
- To diagnose the cause of the code P20BB RAM, a professional mechanic may use a diagnostic scanner to read the code and perform further testing on the reductant heater 'A', wiring, connectors, and PCM.
4. Can I still drive my vehicle with OBDII code P20BB RAM active?
- It is not recommended to continue driving the vehicle with the code P20BB RAM active, as it may lead to increased emissions, reduced fuel efficiency, and potential damage to the vehicle's emissions system.
5. How can I repair OBDII code P20BB RAM?
- Repairing OBDII code P20BB RAM typically involves replacing the faulty reductant heater 'A', repairing any damaged wiring or connectors, and clearing the code with a diagnostic scanner.
6. Are there any DIY tips for fixing OBDII code P20BB RAM?
- DIY repairs for OBDII code P20BB RAM may include checking and cleaning the connectors in the control circuit, inspecting for visible wire damage, and ensuring proper electrical connections.
7. How important is it to address OBDII code P20BB RAM promptly?
- It is important to address OBDII code P20BB RAM promptly to prevent further damage to the vehicle's emissions system, ensure optimal engine performance, and maintain compliance with emissions regulations.
8. Can weather conditions affect OBDII code P20BB RAM?
- Extreme weather conditions, especially cold temperatures, can potentially impact the performance of the reductant heater 'A' and contribute to triggering OBDII code P20BB RAM.
9. How long does it typically take to repair OBDII code P20BB RAM?
- The time required to repair OBDII code P20BB RAM can vary depending on the exact cause of the issue, but it may take a few hours to a full day for diagnosis and repair.
10. Will OBDII code P20BB RAM cause permanent damage to my vehicle if left unaddressed?
- Leaving OBDII code P20BB RAM unaddressed can potentially lead to permanent damage to the vehicle's emissions system, reduced fuel efficiency, and increased emissions output.
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