New Holland ENG 3573 – Engine ECU: urea quality and urea warning level 3

The Selective Catalytic Reduction (SCR) system has detected poor Diesel Exhaust Fluid (DEF / AdBlue) quality, with urea concentration below the acceptable threshold (typically under 30%). This triggers an engine derate and can eventually lock the engine at idle speed.

• T6 Series
• T6.165
• T6.180
• T7 Series
• T8.xxx Series
• CR9090
• CX8080 Elevation
• CX8090 Elevation

1. 1

   Test DEF concentration using a DEF refractometer to ensure it meets the required 32.5% concentration.

2. 2

   Inspect the DEF tank for contamination such as dirt, debris, water, or incorrect fluids.

3. 3

   Inspect the DEF quality sensor (located in the DEF header unit) for heavy crystallization, physical damage, or corrosion.

4. 4

   Check the DEF filter for plugging, which often accompanies poor fluid quality.

1. 1

   Drain the Tank

   Completely drain the degraded or contaminated AdBlue/DEF fluid from the tank.

2. 2

   Clean the System

   If physical contamination (dirt/debris) is found, flush the tank to prevent damage to the new sensor or the dosing pump.

3. 3

   Replace the Sensor

   If the fluid was fresh but the code persists, or if the sensor is physically damaged/corroded, replace the DEF quality sensor assembly.

4. 4

   Replace the DEF Filter

   It is highly recommended to replace the DEF filter during this service to protect the dosing pump and injector.

5. 5

   Refill

   Refill the tank with fresh, clean, on-spec DEF (32.5% urea concentration).

6. 6

   Reset the ECU

   Use a diagnostic tool (such as CNH EST or Iveco E.A.S.Y) to clear the fault codes and perform an 'Engine Restart Counter Reset' to unlock the idle speed and restore full horsepower.