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P20E8 OBD2: Reductant Pressure Too Low

P20E8 OBD2: Reductant Pressure Too Low

What Does the P20E8 Code Mean?

The P20E8 code is triggered when the Powertrain Control Module (PCM) detects that the reductant pressure is too low within the Diesel Exhaust Fluid (DEF) system. This system is critical in reducing harmful emissions from diesel engines by converting toxic nitrogen oxides (NOx) into harmless gases.

What Causes the P20E8 Code?

The P20E8 code can be caused by several factors, including:

  • Failure of the Reductant Pressure Sensor
  • Issues with the Selective Catalytic Reduction (SCR) system
  • Wiring or connector problems within the DEF system
  • Malfunctions in the Powertrain Control Module (PCM)

What Are the Symptoms of the P20E8 Code?

Common symptoms associated with the P20E8 code include:

  • Inability to perform DPF (Diesel Particulate Filter) regeneration
  • Check Engine Light illuminated
  • Reduced engine performance
  • Increased emissions

How Serious Is the P20E8 Code?

The P20E8 code is categorized as an urgent issue. If not addressed promptly, it can lead to significant damage to the vehicle’s exhaust system and may pose safety risks to the driver and passengers due to increased emissions and potential engine performance problems.

How to Diagnose the P20E8 Code

To diagnose the P20E8 code, a mechanic should:

  • Use an OBD-II scanner to confirm the code and check for any related codes.
  • Inspect the Reductant Pressure Sensor and its wiring for any visible damage.
  • Test the SCR system to ensure it is functioning properly.
  • Check the DEF levels and quality as low or contaminated DEF can contribute to the issue.

Common Repairs for the P20E8 Code

Common repairs for the P20E8 code may include:

  • Replacing the Reductant Pressure Sensor
  • Repairing or replacing damaged wiring or connectors
  • Addressing any issues with the SCR system
  • Reprogramming or replacing the Powertrain Control Module (PCM)

How Much Does It Cost to Fix the P20E8 Code?

The cost of repairing the P20E8 code can vary widely depending on the specific issue. On average, repairs can range from $100 to $1,200, depending on whether components like the sensor or PCM need replacement.

Can I Fix the P20E8 Code Myself?

While some DIYers may be able to troubleshoot and repair minor issues, such as checking wiring or replacing a sensor, it is recommended to consult with a professional mechanic for a thorough diagnosis and repair, especially given the urgency of this code.

About JC Landry

JC is the Senior Editor at eManualOnline.com, GarageSpot.com, and Drive-My.com, as well as the Webmaster of TheMechanicDoctor.com, only to name a few. He's been a certified Master Mechanic for 15 years, working for various car dealers and specialized repair shops before turning towards blogging about cars and EVs in the hope of helping the next generation of automotive technicians. He also loves cats, Johnny Cash and Subarus.

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