What does Error Code P20EE mean?
Moderate Issue
DTC Code P20EE indicates that the SCR NOx Catalyst Efficiency is below the threshold for Bank 1. This code is triggered when the Engine Control Module (ECM) detects that the Selective Catalytic Reduction (SCR) system is not effectively reducing NOx emissions, as measured by the upstream and downstream NOx sensors.
What are the symptoms of Error Code P20EE?
- Engine Light ON: The engine light or service engine soon warning light illuminates, indicating a potential issue with the SCR NOx catalyst efficiency on Bank 1.
What causes Error Code P20EE?
- Exhaust leaks can allow unfiltered gases to escape, affecting the NOx reduction process and triggering the code.
- Fuel contamination can alter combustion efficiency, leading to increased NOx emissions and reduced catalyst performance.
- A faulty Diesel Particulate Filter (DPF) can cause backpressure issues, impacting the SCR system's ability to reduce NOx emissions effectively.
- A malfunctioning NOx sensor may provide incorrect readings, leading to improper SCR system adjustments and reduced efficiency.
- Issues with Diesel Exhaust Fluid, such as incorrect concentration or low levels, can impair the SCR system's ability to reduce NOx emissions.
- A faulty Selective Catalyst Reduction (SCR) catalyst may not effectively convert NOx emissions, resulting in the code being triggered.
Find the Root Cause with AI
Analyze symptoms and error codes with artificial intelligence for a precise diagnosis
Fast Diagnosis in under 3 minutes
Precise AI-powered analysis
Free No hidden fees
Data-Driven Over 40,000 reference cases
How to fix Error Code P20EE?
- Preliminary Checks: Begin with a visual inspection of the SCR injection system, exhaust temperature sensors, NOx sensors, and oxygen (O2) sensor harnesses and connectors. Repair or replace any burnt or damaged wiring and connectors.
- Diagnostic Scanner Use: Connect a diagnostic scanner to the vehicle's diagnostic connector. Retrieve all stored codes and freeze frame data, then clear the codes. Test drive the vehicle to see if the PCM enters readiness mode or if the code resets.
- Sensor Data Analysis: Observe the scanner data stream to compare exhaust (pre-cat and post-cat) O2, NOx, and temperature sensor data between engine banks. Use a DVOM to test sensors that show inconsistencies.
- Sensor and Circuitry Testing: Test sensors using the DVOM. Replace any sensors that do not meet manufacturer specifications.
- Catalyst and SCR System Evaluation: If sensors and circuitry are functioning correctly, suspect a faulty catalyst element or SCR system failure. Ensure the DEF reservoir is filled with the correct fluid and is uncontaminated.
- Technical Service Bulletin (TSB) Review: Check for any TSBs that match the vehicle's year, make, model, engine size, and symptoms. This may provide additional diagnostic information.