John Deere 005246.31 – ECU: Aftertreatment SCR Operator Inducement Fault

The Engine Control Unit (ECU) has placed the engine into its final, most severe level of derate because the SCR system's derate countdown timer has reached zero minutes. This is a consequential fault triggered by other active emissions-related issues. When active, the DEF dosing system is shut down for the remainder of the key cycle and DPF regeneration may be inhibited to compel the operator to address the underlying aftertreatment faults.

• 5M Series
• 5100M
• Loaders
• Harvesters
• Forwarders

1. 1

   Retrieve all active and stored DTCs using a diagnostic scanner (look for related codes like 1569.31, 3516.07, 3517, 3516, 2659, or codes related to NOx sensors, DEF pump pressure, or DEF quality to identify the root cause)

2. 2

   Inspect Diesel Exhaust Fluid (DEF) quality, ensuring it is crystal clear, lacks a strong ammonia smell, and has a urea concentration between 31.8% and 33.2%

3. 3

   Check for white DEF crystallization deposits around the dosing nozzle, DEF lines, and tank filler neck

4. 4

   Inspect electrical wiring harnesses, connectors, fuses, and relays for the entire aftertreatment system (NOx sensors, DEF pump, DEF tank sensors) for corrosion, chafing, or heat damage

1. 1

   Address DEF contamination

   If DEF is contaminated or poor quality (DEF quality cause), completely drain the tank, rinse with new DEF (do not use water), and refill with fresh ISO 22241 certified DEF. Replace the DEF dosing unit filter and in-line filter.

2. 2

   Replace faulty NOx sensor

   If indicated by specific NOx DTCs, allow exhaust to cool. Disconnect the electrical connector, remove any mounting hardware, and remove the faulty sensor using a specialized NOx sensor socket. Clean exhaust port threads, apply anti-seize (avoiding the tip), install the new sensor to spec, mount the new sensor module, and reconnect the harness.

3. 3

   Replace DEF dosing unit filter

   If dosing filter is clogged or contaminated, remove the dosing unit filter cover, discard the small equalizing element, and pull out the old filter using the specified tool. Clean housing threads with distilled water, insert the new filter and element, and torque the cover to 23 N·m.

4. 4

   Clear codes and reset system

   Use a diagnostic scanner to clear fault codes. Perform any required calibrations or re-learn procedures (e.g., DPF/SCR sanity check or NOx sensor reset) using John Deere Service Advisor.

5. 5

   Perform verification drive cycle

   Operate the machine under load for 20-45 minutes to allow the system to reach operating temperature. If a DPF clog contributed to the fault, initiate a parked regeneration (takes 30-40 minutes).