Kubota P2303 – Engine Control Module (ECM / ECU): Spark Coil #2 Primary Open/Short-to-Ground

A malfunction in the primary control circuit for Ignition Coil #2. The engine control module has detected that the circuit is either open (broken wire, disconnected plug, or internal coil failure) or shorted to ground.

• Kubota WG Series
• WG1605
• WG1903
• WG2503
• WG3800
• WG972
• Doosan forklifts
• Crown forklifts
• Skyjack boom lifts
• Snorkel boom lifts
• PowerBoss sweepers

1. 1

   Verify Battery Voltage: Ensure the battery is outputting between 10.0 and 16.0 volts, as voltage outside this range can cause erroneous coil codes.

2. 2

   Inspect Connections: Check for loose, corroded, or water-damaged electrical connections at Ignition Coil #2.

3. 3

   Harness Testing: Disconnect the coil and use a multimeter to check the wiring harness between the coil connector and the ECM. Test for continuity (to rule out an open wire) and test for continuity to ground (to rule out a short-to-ground).

4. 4

   Coil Swap Test: Swap Ignition Coil #2 with Ignition Coil #1. Clear the codes and run the engine. If the fault moves to cylinder #1 (logging P2300 or P2301), the ignition coil is internally open/failed and must be replaced. If the code stays as P2303, the issue is in the wiring harness or the ECM.

1. 1

   Disconnect battery

   Turn off the equipment, remove the key, and disconnect the negative battery cable.

2. 2

   Locate ignition coil

   Locate Ignition Coil #2 on the engine valve cover (Kubota WG engines utilize a coil-on-plug design).

3. 3

   Disconnect harness

   Depress the locking tab and disconnect the electrical harness connector from the ignition coil.

4. 4

   Remove retaining bolt

   Remove the retaining bolt securing the ignition coil to the cylinder head/valve cover.

5. 5

   Remove ignition coil

   Pull the ignition coil straight up and out of the spark plug tube.

6. 6

   Inspect spark plug

   Inspect the spark plug for fouling or damage while the coil is removed, and replace if necessary.

7. 7

   Install new coil

   Apply a small amount of dielectric grease to the boot of the new ignition coil and push it down onto the spark plug until it seats fully.

8. 8

   Reinstall retaining bolt

   Reinstall the retaining bolt and tighten it to OEM specifications.

9. 9

   Reconnect harness

   Reconnect the electrical harness connector until it clicks into place.

10. 10

    Test engine

    Reconnect the battery, clear the ECM fault codes using a diagnostic scan tool, and test-run the engine to ensure the misfire/code is resolved.