SY365 excavator T4 emissions, engine torque limit

Release time:

2025-11-27

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Fault symptoms: The engine is limited in torque, operates slowly, the display shows a red engine fault light, a yellow fault light, and the DEF indicator displays 100%.

Cause of failure: The three-in-one unit in the urea tank is damaged.

Troubleshooting process:

① After arriving at the site, park the equipment on a level surface.

② Check that the engine oil, antifreeze, and hydraulic oil levels are all within the normal range.

③ During the test run, it was found that the display showed red and yellow engine alarms, the throttle could not be fully depressed, and the DEF fluid level was at 100%.

④ The DEF level is not at 100%; preliminary assessment indicates a problem with the three-in-one feedback from the urea tank.

⑤ The urea tube’s combined voltage was measured at 23.5V, which is within the normal range.

⑥ The urea pump test, DPF load value check, and SCR test conducted using Cummins software all showed normal results. However, five ECM fault codes—3868, 4677, 4572, 3714, and 3712—were read. These fault codes pointed to the three-in-one module in the urea tank. Since the three-in-one module’s connector was found to have a voltage of 23.5V during testing, and considering that the equipment had not been started for an extended period, the voltage level was within a reasonable range, we concluded that the three-in-one module in the urea tank is damaged.

⑦ There were no new parts available on site. Since the connectors, cooling water pipes, and DEF connectors are all identical, we disassembled another three-in-one unit for a cross-test to troubleshoot the issue.

⑧ The next day, replace the assembly with a new three-in-one unit, and the fault will be resolved.

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Troubleshooting Insights: ① Be sure to use qualified urea DEF solution at the customer’s site.

② When parking for an extended period, be sure to pay attention to the shelf life of the urea.

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