Kubota P2135 – Engine ECU (Engine Control Module / ECM): Accelerator Position Sensor Correlation Error

Triggered when there is an excessive deviation or discrepancy between the output of the two redundant accelerator position sensors (Sensor 1/A and Sensor 2/B). Because the computer cannot determine which sensor is telling the truth, it triggers a safety shutdown, forcing the engine into Limp Mode or Forced Idle, inhibiting DPF regeneration, and limiting engine output.

• V3800-CR-TE4
• V3800-CR-TIE4
• V2403-CR-TE4B
• V2403-CR-TE5B
• WG1605
• WG2503
• WG3800
• SVL65-2
• SVL95-2S
• KX91
• KX121
• KX155
• KX161
• U35
• U45
• U55

1. 1

   Check for Priority Codes: If other Throttle Position Sensor circuit codes exist concurrently (such as P0120, P0220, P0122, P0123, P0222, or P0223), they should take diagnostic priority and be investigated first.

2. 2

   Visual Inspection: Inspect the sensor harness and connectors at the pedal and throttle body. Look for fretting corrosion, bent pins, broken wires, or water intrusion (which can bridge the 5V reference wire to the signal wire).

3. 3

   Voltage & Ground Test: With the key on and engine off, backprobe the connectors to verify a steady ~5.0V reference voltage and solid ground integrity at both sensors.

4. 4

   Live Data Monitoring: Use a scan tool to monitor live data for TPS/APP A and B sensor voltages. Slowly depress the pedal; both signals should change smoothly without high-frequency noise, dead spots, or intermittent dropouts.

5. 5

   Wiggle Test: While monitoring the live data, perform a wiggle test on the wiring harness to see if the voltage drops, which indicates a wiring short or loose connection.

1. 1

   Disconnect Power

   Turn the key switch to the 'OFF' position and disconnect the negative battery cable to protect the ECU.

2. 2

   Clean Connections

   If the diagnostic checks revealed dirt or moisture in the connector, clean the pins with electrical contact cleaner and apply dielectric grease. Re-test the system.

3. 3

   Replace the Sensor/Pedal Assembly

   If the wiring is sound but the sensor has internal dead spots (worn resistive tracks), the sensor or the entire accelerator pedal assembly must be replaced. Unbolt the pedal assembly or throttle sensor, disconnect the harness, and install the new OEM component.

4. 4

   Relearn Procedure

   Reconnect the battery. After replacing the throttle body or sensors, the ECM may require a relearn procedure. Cycle the ignition switch three times, waiting about 10 seconds at each position, to allow the normal idle air control (IAC) learn function to execute.

5. 5

   Clear Codes

   Use an OBD/Kubota diagnostic scanner to clear the P2135 code and test drive the machine to ensure the Forced Idle state is resolved.