Kubota P220F – Engine Control Module (ECM) / Engine ECU: NOx Sensor Heater Control Circuit Range/Performance, Bank 1 Sensor 2

The system detects an electrical fault, open circuit, or performance issue specifically within the heater circuit of the downstream sensor.

• SVL95-2s
• SVL97-2
• SVL97-2C
• M5-091
• M5-111
• M5N-091
• M5N-112
• M6-101
• M6-111
• M6-131
• M6-141
• M7-131
• M7-151
• M7-171

1. 1

   Trace the wiring loom from the downstream NOx sensor (Sensor 2) to the ECM, looking for melted harnesses, chafing, or broken connector tabs caused by extreme exhaust heat.

2. 2

   Unplug the sensor and inspect the connector for water intrusion, corrosion, or damaged pins, which can short out the heater circuit control.

3. 3

   Remove the sensor and inspect the element for heavy soot buildup (from rich fuel mixtures/tuners) or crystallized DEF fluid (from a leaking DEF injector), which can cause premature failure.

4. 4

   Use a digital volt-ohmmeter to check for high resistance or an open circuit in the heater circuit pins on the sensor side, and verify proper voltage supply from the ECM on the harness side.

1. 1

   Preparation

   Turn off the machine, disconnect the battery, and allow the exhaust system to cool completely.

2. 2

   Locate the Sensor

   Locate the downstream NOx sensor (Bank 1, Sensor 2). This is the "Post-NOx" sensor located in the exhaust stream after the SCR catalytic converter / DPF muffler.

3. 3

   Disconnect Wiring

   Unplug the electrical connector linking the NOx sensor to the machine's wiring harness.

4. 4

   Remove the Sensor

   Use a specialized NOx/O2 sensor socket to unscrew the sensor from the exhaust bung. Note: Because of extreme exhaust heat, penetrating oil or a torch may be required to remove a stubborn, seized sensor without damaging the exhaust pipe threads.

5. 5

   Install the New Sensor

   Thread the new OEM NOx sensor into the exhaust bung and tighten it to the manufacturer's torque specification.

6. 6

   Route the Harness

   Reconnect the electrical plug, ensuring the wiring harness is secured and routed safely away from direct contact with hot exhaust pipes to prevent future melting.

7. 7

   Clear Codes

   Reconnect the battery, turn on the machine, and use a diagnostic scan tool to clear the P220F fault code from the ECM. Run the machine to verify the code does not return.