Massey Ferguson E00 – Engine Control Unit (ECU): Downstream NOx sensor internal failure (Short Circuit Error)

The engine's computer has detected a short circuit or implausible signal from the sensor monitoring nitrogen oxide levels exiting the Selective Catalytic Reduction (SCR) system.

• 4707
• 4708
• 4709
• 4710
• T4 (2015-2021)
• 7600 series (7614-7626)
• Global Series
• Tier 4 (T4) tractors (2015-2021)

1. 1

   Verify the Code: Read the full number below 'E00' on the dash to confirm it is exactly 3526.00.

2. 2

   Visual Inspection: Inspect the wiring harness and connector leading to the downstream NOx sensor (located on the exhaust/SCR assembly) for chafing, melting from exhaust heat, or water ingress.

3. 3

   Electrical Testing: Check the connector pins for corrosion or a short circuit to ground, which is the primary trigger for the 3526 short circuit error.

4. 4

   DEF Quality Check: Verify the Diesel Exhaust Fluid (DEF) level and quality, as poor DEF can sometimes cause downstream emissions readings to fall out of plausible ranges.

5. 5

   PC Diagnostics: Use a dealer diagnostic PC/tool to check the signal accuracy from the downstream NOx sensor and verify if the short circuit is active or stored.

1. 1

   Prepare tractor

   Park the tractor on a level surface, turn off the engine, and disconnect the negative battery terminal.

2. 2

   Locate sensor

   Locate the downstream NOx sensor on the exhaust aftertreatment (SCR) pipe.

3. 3

   Disconnect harness

   Disconnect the electrical harness connector for the NOx sensor.

4. 4

   Remove sensor

   Using a specialized NOx sensor socket or a suitable wrench, carefully unscrew the sensor from the exhaust pipe. (If seized, apply penetrating oil and allow it to soak before removal).

5. 5

   Prepare new sensor

   Apply a small amount of high-temperature anti-seize compound to the threads of the new NOx sensor (if it does not come pre-applied). Caution: Do not allow any anti-seize to touch the sensor tip, as this will ruin the sensor.

6. 6

   Install new sensor

   Thread the new NOx sensor into the exhaust pipe and tighten to the OEM specified torque.

7. 7

   Reconnect harness

   Reconnect the electrical harness until it clicks securely.

8. 8

   Reconnect battery

   Reconnect the battery terminal.

9. 9

   Clear fault code

   Connect a diagnostic tool to the tractor's diagnostic port and clear the E00 / 3526.00 fault code from the ECU.

10. 10

    Verify repair

    Start the tractor. You may need to perform a manual/active regeneration via the diagnostic tool to reset the aftertreatment system and verify the repair.