What is SPN 5585 & How to Solve It?

What is SPN 5585:

SPN 5585 is a diagnostic trouble code (DTC) indicating a fault in the Selective Catalytic Reduction (SCR) Catalyst Temperature Sensor Circuit. This sensor monitors the temperature of the SCR catalyst, which is essential for reducing nitrogen oxide (NOx) emissions in diesel engines. A fault with this sensor can cause incorrect temperature readings, impacting emissions control and engine performance.

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Why This Happens

Common causes of SPN 5585 include:

• Faulty or damaged SCR catalyst temperature sensor.
  
• Wiring issues such as open circuits, shorts, or damaged connectors.
  
• Sensor contamination or physical damage.
  
• Faulty Engine Control Module (ECM) or sensor calibration problems.
  
• Excessive exhaust temperatures causing sensor failure.
  
  

How to Fix It

To resolve SPN 5585:

1. Inspect the SCR catalyst temperature sensor for visible damage or contamination.
   
2. Check wiring and connectors for corrosion, breaks, or loose connections.
   
3. Test the sensor’s resistance and voltage signals.
   
4. Replace the sensor if found faulty.
   
5. Repair or replace damaged wiring or connectors.
   
6. Clear the fault code and monitor emissions and engine performance.
   
   

How to Avoid It Before It Happens

To prevent SPN 5585:

• Regularly inspect the SCR system sensors and wiring.
  
• Maintain proper exhaust system temperature to avoid sensor damage.
  
• Use high-quality replacement parts meeting OEM standards.
  
• Perform routine diagnostics to catch sensor issues early.